View
220
Download
0
Category
Preview:
Citation preview
7/30/2019 Legionella Control in Healthcare
1/72
1
An engineering approach to legionella control in Health Care Facilities
ContentsAbstract ................................................................................................................................................... 3
1. Introduction..................................................................................................................................... 4
2. Legionella. .......................................................................................................................................... 5
2.1 What is legionella?........................................................................................................................ 5
2.2 What is Legionellosis? .................................................................................................................. 7
2.3 Legionellosis in Hospitals. ............................................................................................................ 9
3. Legislation......................................................................................................................................... 10
3.1 Irish legislation............................................................................................................................ 10
3.2 Special provisions for Hospitals. ................................................................................................ 12
4. Legionella Control ............................................................................................................................. 13
4.1 The Building services engineers role......................................................................................... 13
4.2 Engineering Control Methods ..................................................................................................... 14
4.2.1 Design and Installation of water storage systems-hot/cold .................................................. 14
4.2.2 Design and installation of water delivery systems-hot/cold................................................. 18
5. Maintenance of water storage and delivery systems......................................................................... 20
5.1 Cold water storage tank cleaning ................................................................................................ 20
5.2 Hot water calorifier cleaning....................................................................................................... 22
5.3 Chlorine dioxide treatment.......................................................................................................... 23
5.4 Automatic flushing systems ........................................................................................................ 27
5.5 TMV and showerhead cleaning .................................................................................................. 30
6. Testing and record keeping ............................................................................................................... 31
6.1 Quarterly water testing................................................................................................................ 31
6.2 Daily chlorine dioxide readings .................................................................................................. 34
6.3 Monthly hot/cold water temperature testing ............................................................................... 367. Interaction with other stakeholders ................................................................................................... 37
7/30/2019 Legionella Control in Healthcare
2/72
2
7.1 Medical staff education ............................................................................................................... 37
7.2 Household/Catering staff flushing regimes................................................................................. 38
7.3 Circulation of information/test results ........................................................................................ 40
8. Case studies....................................................................................................................................... 41
8.1Basildon University Hospital ....................................................................................................... 42
8.2 St Patricks University Hospital.................................................................................................. 45
9. Conclusions....................................................................................................................................... 53
10. Bibliography ................................................................................................................................... 55
11. Appendices...................................................................................................................................... 56
Appendix A ........................................................................................................................................ 57
Appendix B ........................................................................................................................................ 59
Appendix C ........................................................................................................................................ 61
Appendix D ........................................................................................................................................ 63
Appendix E ........................................................................................................................................ 65
Appendix F ........................................................................................................................................ 67
12. Acknowledgements......................................................................................................................... 72
7/30/2019 Legionella Control in Healthcare
3/72
3
An engineering approach to legionella control in Health Care Facilities
AbstractThe purpose of this dissertation is to examine the legionella bacteria and its
implications for the Health care sector from a building services engineering perspective. The
role of the building services engineer is crucial in the control of legionella as the engineer is
involved from the initial stages of designing the water systems for a new building. Thebuilding services engineer may also be responsible for the on-going maintenance of the water
storage and delivery systems in the role of Facilities Manager.
Currently, legislation aimed at controlling the legionella bacteria is in place in Ireland and
special precautions must be taken in Hospitals and other Health Care facilities. I will examine
a Hospital in Ireland that has implemented a stringent legionella control programme and see
what effect such a programme can have on the incidence of high legionella bacteria counts.
Neither of the two Hospitals I have chosen for my case studies employ cooling towers as part
of their ventilation process so I will concentrate more on the risks associated with the hot and
cold water delivery systems as this area is now recognised to be particularly important from a
legionella control point of view.
Having examined the various control methods available, I will be able to draw conclusions as
to their effectiveness and whether or not more needs to be done from both a legislative and
practical point of view to control the legionella bacteria.
7/30/2019 Legionella Control in Healthcare
4/72
4
An engineering approach to legionella control in Health Care Facilities
1.Introduction.The legionella bacteria poses a significant threat to the health of Patients in the Irish health
system today. This threat is not as obvious and has not had as much media exposure as other
risks to hospital in-patients such as MRSA or the winter vomiting bug. Legionella is an
invisible threat and the symptoms of legionellosis are not immediately attributable to thelegionella bacteria. Left unchecked and allowed to flourish in favourable conditions, the
legionella bacteria can multiply with alarming speed to a point where it poses a real threat to
patient health. Because it is a water borne bacteria it can quickly infect an entire hospital
complex as it spreads through the hot and cold water supply.
The role of the Building Services Engineer is crucial in combatting the prevalence and spread
of the bacteria. Proper design and maintenance of the hot and cold water storage and delivery
systems is essential. Engagement of external expertise in the form of a full risk assessment
for legionella allows the engineer to structure a strategy for controlling the bacteria rather
than adopting a piecemeal approach. Interaction between the Building Services Engineer and
all the other professionals and stakeholders in the Hospital is essential as any legionella
prevention programme must involve full participation by all parties from the Medical staff
through to the Household and Maintenance employees. Circulation of information, test
results, prevention initiatives, etc. are all important in ensuring that everyone concerned buys
into the message that legionella is an ever present threat in our Hospitals which cannot andmust not be taken lightly.
An examination of the legionella control methods currently being implemented by a Hospital
here in Ireland and contrasting that with another health care facility which lacked a legionella
control programme and subsequently suffered an outbreak of legionellosis will crystallise and
clarify both the importance of a stringent legionella control programme and the key role that
the Building Services Engineer plays in it.
7/30/2019 Legionella Control in Healthcare
5/72
5
An engineering approach to legionella control in Health Care Facilities
2. Legionella.
2.1 What is legionella?
Legionella is an aerobic bacterium, usually sausage shaped and between 1 and 2 m in
diameter with a thin flagellum or tail-like structure that it uses for propulsion. Compare this
to the diameter of a human hair at approx 100 microns.
Human hair 1x10 m Legionella bacteria 1x10 m
The legionella bacteria was named following investigations into a mystery illness that struck
delegates to the annual convention of the Pennsylvania American Legion at the Bellevue
Stratford Hotel in 1976. Thirty four delegates succumbed to pneumonia like symptoms and
died while over two hundred fell ill but later recovered. The legionella bacteria was
eventually isolated and recognised mainly due to the work of Dr. Joseph McDade from the
U.S. Centre for Disease Control. Because it was a newly discovered bacteria the illness
associated with it was named Legionnaires disease after the first known outbreak and the
bacteria was named Legionella.
http://www.wrongdiagnosis.com/phil/html/legionnaires-disease/2015.html7/30/2019 Legionella Control in Healthcare
6/72
6
An engineering approach to legionella control in Health Care Facilities
Although the exact source of the Pennsylvania outbreak was not found it is now known that
the legionella bacteria thrives in water and survives and multiplies at water temperatures
between 25 and 50C with at optimum temperature of around 35C. Temperatures below
20C inhibit the growth of the bacteria and it is quickly killed at water temperatures over
60C. It can be seen from the table below that optimum conditions for the growth and spread
of the legionella bacteria occur in processes such as spray humidification, cooling toweroperation and domestic hot water applications such as shower facilities. Steam humidification
and low temperature hot water radiators use water at temperatures too high for legionella to
survive while drinking water supplies and AHU cooling coils operate at lower water
temperatures than those favoured by the bacteria.
7/30/2019 Legionella Control in Healthcare
7/72
7
An engineering approach to legionella control in Health Care Facilities
2.2 What is Legionellosis?
Legionellosis is a respiratory illness in people caused by the legionella bacteria. There are
many strains of legionella but the one most often associated with legionellosis is legionella
pneumophila. For an individual to contract legionellosis from a water source, four factors
must be present. These are
1. Multiplication of the legionella bacteria in the water to a level where it cancause infection
2. Creation of an aerosol containing the legionella3. Inhalation of the aerosol by an individual4. Susceptibility of the individual to infection
1. Legionella can and should be assumed to be present to some degree in all water systems.Under favourable conditions the bacteria can multiply to dangerous levels in as little as
seven days. The exact dose of legionella necessary to cause illness in humans is not
known but present guidelines set 1000 coliform units as the level at which remedial action
must be taken if the bacteria is detected. As seen earlier water temperature plays an
important role in the bacterias ability to thrive but another important feature is the
presence of biofilm in the water storage and distribution systems. Biofilm is visible to the
eye and is the slimy substance found on the inner surface of distribution pipework. It is
made up of naturally occurring amoebae and protozoa in the water. The legionella
bacteria is a parasite of these organisms and can survive inside them even when othernutrients are in short supply. The legionella bacteria is also less susceptible to water
treatments involving the use of free chlorine whilst sheltering within this biofilm. Other
sources of nutrient for the legionella bacteria can come from poorly maintained and
uncovered water storage tanks, poor hygiene standards during installation or remedial
works on water distribution pipework and use of nutrient rich plumbing products such as
certain pipe jointing compounds and hemp.
7/30/2019 Legionella Control in Healthcare
8/72
8
An engineering approach to legionella control in Health Care Facilities
2. If the biofilm in the water supply network is infected with legionella and it becomesdislodged for any reason, this can lead to a rapid release of large amounts of infectious
bacteria. Possible causes of such dislodgement would include local repair or expansion
works which necessitate the breaking of pipework joints and not flushing new
installations thoroughly before initial use. If this release of bacteria coincides with the
formation of a water aerosol at the delivery point then the possibility for human infectionexists. Aerosol formation may take place in cooling towers, showering facilities
connected to hot and cold water supplies, decorative fountains and spas to name just a
few.
3. For the legionella bacteria to cause legionellosis in humans it must gain access to thelungs. This is the only route that will cause infection. Consuming water does not cause
legionellosis and there is no evidence of person to person contamination.
4. The incidence and severity of infection depends on the susceptibility of the individual andtheir overall health condition. Permanent reduced lung capacity may occur following
infection. The following people are thought to be at higher than average risk of
contracting legionellosis
Older peopleover age 40- Males People who smoke People who drink to excess People with suppressed immune systems. For example HIV sufferers or organ
transplant recipients
People with underlying health problems such as diabetes, heart complaints andrespiratory problems. It is thought that stroke sufferers and people with
alcohol addictions are at greater than normal risk as their choking reflex may
not be functioning properly and this may allow swallowed liquid containing
traces of legionella to be aspirated into the lungs.
7/30/2019 Legionella Control in Healthcare
9/72
9
An engineering approach to legionella control in Health Care Facilities
2.3 Legionellosis in Hospitals.
Hospital Management has an important role to play in implementing and prioritising any
legionella control programme. The duty of care that exists in a hospital situation differs
from a hotel or guesthouse in that the hospital patient is normally already vulnerable to
infection due to medication or a suppressed immune system. In a psychiatric hospital patients
may have the added risk of being prone to self-harming. There is a risk of self-inflicted scald
injuries in such instances if patients are allowed to regulate their own shower water
temperatures. Strong medication such as anti-depressants may lead to patients becoming
immunocompromised and more open to legionella infection.
Hospitals by their nature tend to be large buildings or a collection of buildings and will
probably have extensive and isolated water storage facilities. Cold water storage tanks may or
may not be designed and installed to modern standards. There may be several plant rooms on
site supplying domestic hot water to different buildings. Hot and cold water delivery
pipework will tend to be very extensive, may or may not be properly insulated throughout its
length and may or may not be properly marked on layout drawings. All of these factors need
to be taken into account by the building services engineer at the initial planning stages for a
new building and when planning a legionella control programme for an existing building or
complex.
7/30/2019 Legionella Control in Healthcare
10/72
10
An engineering approach to legionella control in Health Care Facilities
3. Legislation
3.1 Irish legislation.
The main legislative provisions in relation to the control and prevention of legionella
infection in Ireland are found in Health and Safety at Work legislation and some are modelled
on existing British legislation. The relevant acts are
The Safety, Health and Welfare at Work Act 2005 The Safety, Health and Welfare at Work ( General Application ) Regulations
2007
The Safety, Health and Welfare at Work ( Biological Agents ) Regulations1994, amended in 1998
The Safety, Health and Welfare at Work ( Chemical Agents ) Regulations2001
The Infectious Diseases Regulations 1981 The UK Health and Safety Commission (HSC) document, Legionnaires
DiseaseThe control of legionella bacteria in water systems - Approved Code
of Practice L8;
The Health Protection Surveillance Centre (HPSC) - The Management oflegionnaires disease in Ireland (Endorsing HSC Approved Code of Practice);
Health Technical Memorandum 04 01 Water Systems: The control ofLegionella, hygiene, safe hot water, cold water and drinking water systems.
Part A Design, Installation & testing;
Health Technical Memorandum 04 01 Water Systems: The control ofLegionella, hygiene, safe hot water, cold water and drinking water systems.
Part B Operational Management.
7/30/2019 Legionella Control in Healthcare
11/72
11
An engineering approach to legionella control in Health Care Facilities
The 2005 Act applies to employers, employees and the self-employed and sets out the general
guidelines for managing risks. Section 19 of the act requires the employer or any person
responsible for the safety of the workplace to carry out a risk assessment. The risk assessment
relates to employees and people not employed but availing of the buildings facilities, for
example hospital patients. A safety statement must be prepared setting out how any risks are
managed.
Section 16 of the 2005 Act states that designers, manufacturers and suppliers of articles have
a duty of care to ensure that plant and machinery is free from risk to health when used
properly. This means that the building services engineer must ensure that the design of the
hot and cold water systems in a building is to a standard that will not promote the growth of
harmful bacteria such as legionella.
Under the 1994 ( Biological Agents ) regulations legionella pneumophila is listed as a group
2 biological agent. This means that it is capable ofcausing disease in humans but is unlikely
to spread to the wider community and is treatable with antibiotics. Regulation 3f of the act
deals with situations where it is not intended for a person to intentionally come into contact
with a biological agent but where such contact may occur during cleaning and maintenance
operations. This would be the case when facilities personnel undertake cleaning of existing
water distribution systems.
The 2001 ( Chemical Agents ) Regulations pertain to legionella insofar as they set out the
standards required when using chemicals such as biocides and disinfectants to clean water
storage and delivery systems.
Under the 1981 Infectious diseases regulations, legionellosis is a statutorily notifiable disease
and any suspected cases must be made known to the local health authority .Suspect cases
must be investigated and any remedial works necessary to remove the source of the infection
carried out.
7/30/2019 Legionella Control in Healthcare
12/72
12
An engineering approach to legionella control in Health Care Facilities
The National Guidelines for the Control of Legionellosis in Ireland 2009 sets out the most
up to date guidelines available for the monitoring, prevention and control of legionella in this
country. It sets out best practice guidelines for carrying out risk assessments for legionella,
for designing and maintaining water storage and delivery systems and for record keeping and
legionella testing regimens. It also recommends that the Irish Government introduce
legionella specific legislation without delay concerning
1. Maintenance and disinfection of any equipment capable of producing anaerosol contaminated with legionella
2. Statutory notification by owners of high risk sites such as cooling towers3. The setting up of a statutory authority for the monitoring of these and other
high risk sites
3.2 Special provisions for Hospitals.
The National Guidelines for the Control of Legionella in Ireland 2009 sets out the
legionella control measures to be undertaken in Hospitals based on the legionella policies and
procedure of the HSE South Eastern health Authority. Under these guidelines the Manager or
Chief Executive Officer of the Hospital is responsible for the appointment of a nominated
responsible person who is tasked and adequately resourced to carry out duties relating to
legionella control. It recommends the setting up of an Environmental Monitoring Committee
for each Health Authority area. At local Hospital level this could be an Infection Control
Committee. It recommends that a building services engineer or equivalent be a member of
that committee and fulfil the following roles.
Ensure new heating and ventilation systems are designed to the correct standards Carry out a risk assessment of the water storage and delivery systems Ensure any system modifications and works are carried out in accordance with best
practice guidelines
Ensure all routine system inspections, maintenance and disinfections are carried out ina timely manner
7/30/2019 Legionella Control in Healthcare
13/72
13
An engineering approach to legionella control in Health Care Facilities
Delegate water testing and temperature monitoring to relevant personnel Disseminate legionella test results and other relevant information to other
stakeholders
Ensure all records are properly kept, regularly updated and available for inspection onrequest
4. Legionella Control
4.1 The Building services engineers role
The building services engineer can and must play a central role in controlling the legionella
bacteria in hospitals and other health care facilities. Proper planning of the water storage and
delivery systems at the design stage will minimise the risk of legionella colonisation at a later
stage and lessen the need for costly remedial work and high on-going maintenance charges.
The engineer must understand where the main legionella risks occur in hot and cold water
systems and then try to design out as many of these risks as possible. Examples of avoidable
risks could include long runs of poorly insulated cold water delivery pipework through heated
voids where temperature gain in the cold pipe becomes inevitable. Also wrongly sized
calorifiers may mean the target temperature of 60C may not be realised because of heavy
load resulting from poor planning at the design stage. An understanding by the design
engineer of the building management system chosen at the design stage of a building and the
applications of the BMS to legionella prevention is very important. The BMS can be
invaluable for automatic monitoring of calorifier flow and return temperatures, automatic
temperature monitoring at cold water storage facilities and automatic monitoring of chlorine
dioxide dosing systems. Temperatures outside design parameters can be quickly sensed and
alarmed by the BMS allowing the operator to take any necessary remedial action at an early
stage.
In the role of Facilities Manager, the building services engineer plays a pivotal role in
ensuring the on-going maintenance and monitoring of the various components that make up
7/30/2019 Legionella Control in Healthcare
14/72
14
An engineering approach to legionella control in Health Care Facilities
the hot and cold water supply system. The engineer must ensure that any works which
involve breaking into the hot or cold water supply are carried out to standard so that
pollutants are not introduced into the system. Breaking the supply pipework in an already
infected system can lead to massive amounts of the legionella bacteria being released into the
water flow and possibly to outlets being used by already vulnerable hospital patients. The
engineer fulfilling the role of Facilities Manager is responsible for ensuring that all systemmaintenance and disinfection is carried out in a timely manner and that all records are
properly filed and available for inspection by relevant authorities.
Of all the health care professionals involved in ensuring that the legionella bacteria remains a
diminished threat, it is the building services engineer who has the most influence because
through his understanding of the bacterias requirements for growth, the engineer can break
the chain of infection and directly minimise the risk to patients.
4.2 Engineering Control Methods
4.2.1 Design and Installation of water storage systems-hot/cold
The design stage of the water storage system is crucial in minimising the risks from
legionella. If the proper precautions are not designed in at this stage the storage systems may
become breeding grounds for the bacteria which can then spread through the delivery pipe
network. The initial sizing of the cold water storage tank is important but not easy as it will
be based on forecast use and projected patient and staff numbers which may or may not be
realised in reality. Therefore the initial sizing should take this into account and make
allowance for possible future alterations to the stored volume. This can be achieved through
the use of variable volume supply valves which can increase or decrease the volume of water
stored without the need to physically adjust the supply ball valve. It is important that no more
than the 24 hours of water storage capacity recommended is provided for as water which is
allowed to remain in the storage tank for longer than this is prone to increased temperature.
This may not seem to be a problem on a cold day in January but in mid-summer and bearing
in mind that the water will inevitably gain even more in temperature as it travels through the
7/30/2019 Legionella Control in Healthcare
15/72
15
An engineering approach to legionella control in Health Care Facilities
delivery pipework, this can be the difference between maintaining the cold supply below the
necessary 20C at the outlet or not. Adequate insulation and a tight fitting and insulated
hinged access cover are necessary to protect the cold water storage tank from excesses of heat
and cold. Light must not be allowed to penetrate the tank as this encourages the growth of
algae which will provide a nutrient base for the legionella bacteria.
The positioning of the inlet and outlet pipes also plays an important role in water storage tank
design. The inlet and outlet must not be positioned on the same side of the storage tank as this
can lead to short circuiting of the water and insufficient mixing of the water within the tank. I
have taken temperatures from a storage tank wrongly plumbed in this way and found a swing
of more than 1C across a relatively small tank containing 7,500 litres. The negative effects
of such short circuiting are even more obvious in interconnected tanks. In this situation the
unplumbed tank will effectively have little or no turnover of water except in periods of very
high usage. If allowed to stagnate for long periods this water is likely to become increasinglycolonised by legionella which may be drawn into the supply network during heavy use
Mains water
supply
Insulation
all around
tank
Typical Cold Water
Storage Tank
Alternative
Cold WaterService (CWS)
outlet
Cold Water Service
(CWS)
Lid
Screened
vent
Screened
overflow
Air gap to meet water
regulations
Drain
7/30/2019 Legionella Control in Healthcare
16/72
16
An engineering approach to legionella control in Health Care Facilities
periods if the plumbed tank cannot meet the demand. Interconnected cold water storage tanks
should be individually served by separate supply valves and the outlet from each tank should
be positioned as far from the inlet pipe as possible.
The picture above is of the interior of a very small water storage tank of just 2,500 litres. The
inlet to the tank is at the right side of the photo and the outlet is at the top of the photo. The
distribution of the grit at the bottom of the tank shows very clearly that the water is taking the
shortest route between the inlet and outlet and the water at the bottom and left sides of the
photo is stagnating. Imagine how much this undesirable situation would be magnified in a
wrongly plumbed storage tank of 20,000 litres which is not an uncommon size for a cold
water storage tank in a large facility
7/30/2019 Legionella Control in Healthcare
17/72
17
An engineering approach to legionella control in Health Care Facilities
The sizing of the hot water calorifiers is critical in maintaining the proper temperature within
the vessel during all load periods. Again this sizing will be based on projected use if the
calorifier is being designed for a new building and once installed it will be very costly and
labour intensive to replace it later so accurate sizing is important. Calorifiers are naturally
cooler at the cold water inlet level and this lower level is also the area most likely to have
accumulations of debris and sludge. This area of the calorifier is more susceptible tolegionella contamination than the hotter upper strata. If the calorifier is undersized, water
from this lower infected area of the calorifier may be drawn into the system pipework during
high use periods. Modern sizing methods allow for generous margins and there is little
danger of under sizing of new installations but care must be taken when planning to increase
the load on older calorifiers to serve a new hospital wing for example. There are two ways to
overcome the problem of reduced temperature near the calorifier base. A circulating pump
can be fitted within the calorifier to mix the water to a uniform temperature. However this
approach disrupts the water stratification within the vessel and so can only be undertaken
when the calorifier is not discharging. This approach is not very practical in a busy hospital
with 24 hour operation. A more realistic approach is to ensure the maximum possible
insulation is applied to the base of the calorifier and the addition of localised electrical trace
heating should be considered. If a legionella outbreak occurs in a hospital, one of the quickest
remedies available is to thermally treat the entire hot water storage and delivery systems. This
involves raising the calorifier temperature to 80C and passing this superheated water
through the delivery pipework for one hour under controlled conditions. The calorifier must
be designed to be capable of reaching and maintaining this raised temperature if necessary.
Finally all calorifiers should have drain points fitted at the base to allow for cleaning and the
taking of samples for legionella testing.
7/30/2019 Legionella Control in Healthcare
18/72
18
An engineering approach to legionella control in Health Care Facilities
4.2.2 Design and installation of water delivery systems-hot/cold
Successfully minimising legionella colonisation of the hot and cold water delivery pipework
begins with implementing good mechanical design and installation practices to include the
following
Sediment traps at the bottom of long vertical runs of pipework and flushing points onlong horizontal pipe runs to allow periodic purging of the lines
Use valves that do not encourage the build-up of sediment and other trapped objects atthe valves themselves. Globe and gate valves will allow a certain amount of debris to
accumulate and this could be a nutrient source for bacteria. Ball valves in the fully
open position will not trap debris and should be favoured
Globe valve Gate valve Ball valve
Smaller diameter tap offs from main pipes should be taken from the top half of thepipe so as to minimise the risk of creating a debris trap at the branch. All pipe burrs
should be removed for the same reason.
Hot and cold pipe runs must be properly insulated with the recommended thickness ofinsulation material. When installed in close proximity to each other, the hot pipe
should be above the cold so as to minimise any possible heat transfer.
It is good practice to finish a pipe run at a frequently used outlet such as a wc toensure regular flushing of the entire pipe length
http://www.google.ie/imgres?imgurl=http://upload.wikimedia.org/wikipedia/commons/thumb/5/52/Seccion_valvula_de_bola.jpg/250px-Seccion_valvula_de_bola.jpg&imgrefurl=http://en.wikipedia.org/wiki/Ball_valve&h=222&w=250&sz=11&tbnid=ZlDtmMNWnO_VcM:&tbnh=83&tbnw=94&prev=/search?q=ball+valve&tbm=isch&tbo=u&zoom=1&q=ball+valve&docid=dMisyfO_USd7mM&hl=en&sa=X&ei=mLaaToq8PMfBhAfd3KCSBA&sqi=2&ved=0CGQQ9QEwAQ&dur=3112http://www.google.ie/imgres?imgurl=http://championindustrialjamaica.com/product_images/b/447/Globe_Valve_CWT__72220_zoom.jpg&imgrefurl=http://championindustrialjamaica.com/products/Globe-Valve.html&h=360&w=360&sz=27&tbnid=ofMIrvRRM5BvnM:&tbnh=90&tbnw=90&prev=/search?q=globe+valve&tbm=isch&tbo=u&zoom=1&q=globe+valve&docid=qv-n7G_yvffeFM&hl=en&sa=X&ei=-baaTt_1NJO4hAf5kbWKBA&sqi=2&ved=0CEMQ9QEwAw&dur=8517/30/2019 Legionella Control in Healthcare
19/72
19
An engineering approach to legionella control in Health Care Facilities
Pipe runs should be reviewed regularly to ensure that no dead legs have been createddue to areas such as wards being taken out of use. If an area is out of use temporarily,
a programme of flushing of outlets must be implemented until the area is brought
back into use again. If services are to be permanently halted in an area then the hot
and cold supplies should be switched off and the pipework removed back to the
furthest junction possible so as not to leave any dead legs in the system which couldharbour legionella.
The choice of pipe material used and the way it is jointed is also important. Debatecontinues about the merits or otherwise of using modern plastic piping in hot and cold
water supply systems. Critics quote its poor mechanical strength and need for
extensive support brackets compared to copper tubing. Poorly installed plastic pipe
may have extensive sagging along its length which could negate some of the benefits
of flushing. There is a question mark over whether or not leaching of material maytake place from plastic pipe over time, material which could add to the nutrient base
available to the legionella bacteria. Copper remains the material of choice and is
especially suitable for use with modern chlorine dioxide plant as it is resistant to
chlorine at recommended levels. Pipe jointing materials such as hemp and linseed oil
based compounds should never be used in potable water systems as they are
biodegradable and provide a nutrient rich source for bacteria. Modern compression
fittings as well as the use of soldered joints negate the need to use such products.
Avoid using jointing products such as hemp which could favour the growth of legionella
7/30/2019 Legionella Control in Healthcare
20/72
20
An engineering approach to legionella control in Health Care Facilities
5. Maintenance of water storage and delivery
systems
5.1 Cold water storage tank cleaning
The cold water storage tank could be a vulnerable link in the water supply chain.
Traditionally the cold storage tank suffered from the out of sight, out of mind mentality as
by its nature the cold water tank is usually situated high up on a rarely visited roof or
inaccessible attic space. Uncovered tanks with little or no insulation against heat or cold were
the norm up to quite recently and unfortunately can still be found in operation today.
Uninsulated cold water storage tanks will suffer huge temperature swings due to the effects of
sunshine in the summer and frost in the winter. An un-insulated tank situated on a roof or in
an attic space will undoubtedly break the recommended cold water temperature maximum of
20C during the summer months. If light is allowed to penetrate into the tank due to badly
fitting covers or no covers at all, this will encourage the growth of algae in the tank,
especially at the water line and this algae will provide a nutrient base for the legionella
bacteria. Cleaning of the water storage tank on an annual basis is the key to maintaining the
water quality within the tank. It is important that cleaning is undertaken by trained personnel
and that the task is governed by a standard operating procedure. Staff must adhere to the
SOP and proper records must be kept. A typical SOP for water storage tank cleaning should
include the following:
Notice must be given to the occupants of any parts of the building to be affectedduring the water outage period
Drawings of the supply system downstream of the storage tank to enable theoperatives to valve off and isolate the tank correctly
Instructions to the cleaning operatives about personal protective equipment to be used
7/30/2019 Legionella Control in Healthcare
21/72
21
An engineering approach to legionella control in Health Care Facilities
Step by step instructions about how precisely the cleaning is to be carried out, whatchemicals are to be used for disinfection and in what quantities
Instructions around any flushing of the supply system downstream of the tank withthe diluted chemical disinfectant and subsequent flushing with clean water.
Proper record keeping to include the date of the cleaning, the names of the operativesinvolved and a record of any chemicals used and the quantities.
This 19,000 litre cold water storage tank had a poorly fitted lid and no insulation and is
situated in an area that suffers from huge solar gains in the summer. This tank was brought up
to standard by boarding out the gap between the bund wall and the tank and providing an
access stairs for cleaning and maintenance. The walls of the tank were cladded with 60 mm
of kingspan insulation panels secured with exterior batens. The roof of the tank was fitted
with 80 mm kingspan rigid interlocking panels into one of which a hinged access lid was cut.
Note the plumbing of the water meter to this tank. The meter is fitted in such a way that the
unused leg at the top of the photo can be left in a draining position so that it cannot provide a
potential breeding area for the legionella bacteria.
7/30/2019 Legionella Control in Healthcare
22/72
22
An engineering approach to legionella control in Health Care Facilities
5.2 Hot water calorifier cleaning
It is convenient to assume that once the calorifier temperature is kept above 60C, then this
part of the water delivery chain is safe from a legionella risk point of view. However this is
not the case. As we have seen already, debris and sludge gathers at the lowest point of a
calorifier over time and coupled with the lower return water temperatures entering the vessel
in the vicinity of these deposits, a favourable environment for the legionella bacteria may
exist. It is important therefore that the hot water calorifier is fully cleaned out on a regular
basis. This is not necessary every year but a good rule of thumb is to clean the calorifier,
check it again after three years and depending on its condition then, the cleaning interval can
be kept at three years or extended to a maximum of five years. This cleaning should be
undertaken by trained personnel with a working knowledge of the system as care must be
taken to ensure that no damage is caused to the heater battery coils or calorifier seals. Extra
care must be taken to ensure that debris from the calorifier is not allowed to enter the delivery
pipework during cleaning as this could potentially release legionella bacteria directly to the
end user water outlets.
Heater battery removed from a calorifier for cleaning, showing accumulated debris and
deposits which could provide a beneficial environment for bacteria
7/30/2019 Legionella Control in Healthcare
23/72
23
An engineering approach to legionella control in Health Care Facilities
5.3 Chlorine dioxide treatment
Chlorine has been recognised for a long time as being a useful disinfection agent in water
storage and supply systems. Hyper chlorination of water supply systems found to be infected
with legionella is an important tool in the battle against the bacteria, especially in Health care
facilities where higher than average numbers of susceptible people are concentrated. In such
situations and following a positive result for legionella, the facilities personnel will typically
raise the chlorine level in the affected cold water storage tank to 50 ppm and maintain it at
this raised level for one hour. The hyper chlorinated water is then flushed through the system
until a concentration of 30 ppm is measurable at the furthest sentinel cold outlet. The sentinel
tap should continue to be flushed for one hour and other cold outlets opened also. This
procedure is usually carried out in conjunction with a thermal treatment of the hot water
calorifier and supply pipe network. Similar to the procedure with the cold supply, the hot
water calorifier temperature is raised to 80C under controlled conditions and maintained at
this raised level for one hour before being released into the supply pipe system. The furthest
sentinel hot outlet is then opened and run for one hour to ensure that the entire supply system
is thermally treated at the raised temperature.
The process described above is however only designed for emergency use. It is not feasible or
desirable to maintain high levels of chlorine in a water supply system as a legionella control
measure. There are several reasons for this
Chlorine increases the rate of corrosion in copper pipes. A study of this by theUniversity of Iowa showed an increase in leaks on the supply system from 0.17 to 5
per month
High chlorine levels in water can lead to the formation of organic compounds calledtrihalomethanes and these have the potential to cause cancer. Another study by the
University of Iowa found that when the level of free chlorine in water was raised to
4ppm, the level of trihalomethane rose to 200g per litre or double the recommended
amount
7/30/2019 Legionella Control in Healthcare
24/72
24
An engineering approach to legionella control in Health Care Facilities
The benefits of using chlorine in water delivery systems can however continue to be realised
through its use as chlorine dioxide. Chlorine dioxide is produced by reducing sodium chlorate
in an acid solution. Chlorine dioxide in its gaseous state is highly unstable and therefore the
product is normally produced on site in a chlorine dioxide generator and injected directly into
the water stream to be treated. Some of the benefits of using chlorine dioxide in the cold
mains supply include
Chlorine dioxide is a registered biocide Proper use involves dilution in the treated water at concentrations too low to risk
corrosion of the delivery pipe network
Chlorine dioxide will tolerate substantial swings in the pH of the water Bacteria cant build up a tolerance against chlorine dioxide over time.
Chlorine dioxide works by initially destroying the biofilm present in all parts of the waterdelivery system and then preventing its re-growth. As noted already, this biofilm layer is
made up of amoebae and protozoa which naturally occur in water, as well as deposits of
organic material. Once the biofilm layer is destroyed, the legionella bacteria which parasites
on the biofilm organisms can no longer establish a foothold and is easily flushed out of the
system before it can form colonies large enough to cause legionellosis. The cleaning effect
that chlorine dioxide achieves on a water delivery system is easily observed in the following
areas
The water storage tank, especially at the water line where biofilm is likely to occur System ballcocks splashed by treated water are clean while those in untreated tanks
have biofilm deposits
Toilet cisterns served by chlorine dioxide treated water are clean while untreatedcisterns have biofilm present
The strainers of thermostatic mixing valves stay free of biofilm and other deposits Shower heads are cleaner
7/30/2019 Legionella Control in Healthcare
25/72
25
An engineering approach to legionella control in Health Care Facilities
The main disadvantage of using chlorine dioxide in legionella control programmes is that it
can lead to complacency. Unfortunately chlorine dioxide has come to be seen in some
quarters as a silver bullet for legionella but it is not. It is a useful tool in a comprehensive
legionella prevention programme, but Facilities Managers adopting a fit and forget
approach are likely to be disappointed.
The chlorine dioxide dosing system shown here, though only fitted in the last three years is
now considered to be old technology because it uses a three stage process beginning with the
blue container on the left which contains hydrochloric acid. This acid is diluted and passed
over the crystals in the white canisters where ion exchange takes place. Finally the solution is
delivered to the catalytic converter which is the grey cylinder on the right and the formation
of the chlorine dioxide gas is speeded up. This gas is then injected via a metering pump into
the incoming cold main. Failure at any point of the three stage process means that chlorine
dioxide is not being produced and the system is not being protected. Experience by the author
of working with this system shows that excellent results are possible but very close and
labour intensive monitoring is essential to ensure the un-broken delivery of chlorine dioxide
to the water stream. This system also exposes the operator to hazardous chemicals and the ion
exchange canisters are pressurised, creating another potential risk. There is also a rapid falloff in the efficiency of conversion of constituents to chlorine dioxide in older on site
7/30/2019 Legionella Control in Healthcare
26/72
26
An engineering approach to legionella control in Health Care Facilities
generators. Modern systems produce chlorine dioxide in a simpler and much less hazardous
way as they do not use corrosive acids. The system output is also improved with up to 95%
conversion to chlorine dioxide being achieved and maintained.
Tristel Technologies in-line dosing unit
This example of a modern chlorine dioxide dosing system has several advantages over the
older arrangements.
It uses two low risk chemicals, namely sodium chlorite and citric acid There is no fall off or gradual decline in the production of chlorine dioxide An alarm function on plant failure Lightweight and compact unit
7/30/2019 Legionella Control in Healthcare
27/72
27
An engineering approach to legionella control in Health Care Facilities
5.4 Automatic flushing systems
A viable legionella colony can develop in a water supply system in as little as seven days.
Areas where water services are infrequently or intermittently used are at risk. In Health care
facilities it is not uncommon for entire wards to be taken out of use for extended periods. This
could be due to budgetary constraints or refurbishment. Even in areas that are continually
occupied it is possible that one or more water outlets may receive little or no use. An example
would be a store room on a hospital ward that has always had a hand wash basin because it
was originally designed to be an examination room but is now stocked to the ceiling with
boxes, wheelchairs, Patient property, etc. Such a basin is seldom if ever used and the hot and
cold supply to it is at high risk of harbouring legionella.
Instigating a flushing regime as part of a legionella control programme involves the manual
flushing of infrequently used water outlets on a weekly basis. This is a labour intensive
exercise and in a Hospital environment is usually allocated to the Household staff. The reason
for this is that the individual Household staff member will know his or her allocated ward or
area intimately and will have a much better knowledge of what rooms are or are not in
regular use and hence what outlets will need to be flushed.
The labour intensive nature of such a manual flushing regime has already been noted and an
available or willing pool of staff may not be present in all situations. Automated systems are
now available for flushing of outlets and consideration of their use is definitely recommended
on new build projects. Retrofitting to existing systems is not however labour intensive, overly
intrusive or prohibitively expensive and should also be considered by the building services
engineer.
7/30/2019 Legionella Control in Healthcare
28/72
28
An engineering approach to legionella control in Health Care Facilities
The aquaflush unit shown here is similar to others available on the market. It can be
programmed to perform temperature checks on the hot and cold supply to sentinel outlets at
pre scheduled intervals.
It will also perform an automatic flushing of the hot and cold sentinel outlet on a pre-set time
schedule and send the resultant data wirelessly to a central monitoring station or building
management system.
The main benefits associated with automating the flushing of outlets include
Cost. Once installed there are no on-going labour or travel costs such as would be thecase with a manual system
Safety, the flushed water goes directly to drain Quick and easy installation Elimination of human error Wireless communication Accurate on-going record keeping
The main disadvantage of automated flushing is the fit and forget mentality that such
systems can nurture. An initial survey may identify what outlets need to be fitted with
7/30/2019 Legionella Control in Healthcare
29/72
29
An engineering approach to legionella control in Health Care Facilities
automated flushing devices but that survey will only be relevant for one weekthe time it
takes a legionella colony to become viable-. If an outlet subsequently goes out of use for
whatever reason and goes un-noticed, the system will again be vulnerable. The implications
of removing on-going human monitoring and intervention in any flushing regime need to be
carefully considered before deciding on the merits of automated flushing.
The shower outlet is recognised as probably posing the highest risk of legionella
contamination in health care facilities. Production of an aerosol containing traces of
legionella is more likely at a shower head that in most other situations where vulnerable
patients are likely to come into contact with the water supply. The nature of showering means
that water droplets are likely to enter the mouth and may possibly be aspirated into the lungs
of already immunosuppressed patients.
Self- purging shower pipework arrangement showing extra connection to drain
The recognition of this risk has led to the development of self- purging showers such as the
one shown here. The red and blue pipes represent the hot and cold supply to the mixing
valve. When the shower is turned on, rather than immediately supplying water to the
showerhead, the flow is instead directed through the white pipe to the waste water drain
7/30/2019 Legionella Control in Healthcare
30/72
30
An engineering approach to legionella control in Health Care Facilities
shown here in green through a special air vent which stops foul odours returning and
eliminates the possibility of any aerosol formation. When the supply pipes have been purged
and the desired supply temperature reached, the valve redirects the flow to the showerhead as
normal. In some models the spray plate on the shower head automatically detaches or moves
away from the rest of the showerhead when the shower is turned off so as to fully drain all
remaining water from the vicinity of the showerhead. This results in a fully dry showerheadwhere legionella is unable to survive
5.5 TMV and showerhead cleaning
Thermostatic mixing valves take separate hot and cold supplies and mix them in a pre-
determined ratio to produce water at approximately 41C which is the standard temperature
for shower water supplies. However water at this mixed temperature is also ideal for
legionella and any dirt or debris which may have accumulated at the TMV will provide a
foothold for the bacteria to grow. Showerheads are at similar risk as they are also in direct
contact with water at legionella friendly temperatures and this water may remain in the
showerhead fitting after the supply is switched off. The presence of limescale or other debris
in the showerhead will exacerbate the situation.
Proper cleaning and maintenance of TMVs and showerheads is therefore very important and
must be carried out at regular intervals as laid down in the HPSC guidelines. Thermostatic
mixing valves must be inspected and cleaned annually and showerheads quarterly. Standing
operating procedures for cleaning of both pieces of equipment must be produced by the
building services engineer and followed by the cleaning operatives involved. The SOP must
provide step by step instructions on the proper cleaning procedures to be followed as well as
other important considerations such as proper use of personal protective equipment. Proper
records of all cleaning must be maintained and made available to relevant authorities on
demand.
7/30/2019 Legionella Control in Healthcare
31/72
31
An engineering approach to legionella control in Health Care Facilities
6. Testing and record keeping
6.1 Quarterly water testing
Sampling and testing of the hot and cold water supply is a vital part of any legionella control
programme. Test results will allow the engineer to take a coordinated approach to planning
the legionella prevention programme and tests which show no instances of legionella
infection are an on-going verification of an effective prevention programme. Testing of
samples must be carried out by an accredited laboratory.
At the initial stages of a legionella prevention programme, testing should be carried out every
three months and all hot water calorifiers and cold water storage tanks should be represented
at each testing interval so that a complete assessment of the entire site can be made.
Following a series of clear test results, consideration may be given to extending the testing
interval to six monthly if there are budgetary constraints, but a better approach may be to
leave the testing interval at quarterly and cut down on the number of samples taken. This
approach means there is still a check on the prevention programme at timely intervals and
any instances of positive results can be actioned without undue delay. The Health Protection
Surveillance Centre sets out the following guidelines for dealing with positive legionella
results depending on the number of coliform units cfu - of the legionella bacteria
discovered.
7/30/2019 Legionella Control in Healthcare
32/72
32
An engineering approach to legionella control in Health Care Facilities
100 but
7/30/2019 Legionella Control in Healthcare
33/72
33
An engineering approach to legionella control in Health Care Facilities
If the remedial action fails to achieve reduced levels of legionella or if the system is found on
retesting to be clear and then subsequently becomes rapidly re-infected, this necessitates an
examination of the entire water supply network to try to ascertain the cause. If legionella is
breeding freely in the water supply system, this obviously means that favourable conditions
are occurring which encourage such growth. These conditions may be caused by recent works
carried out on the system which may have allowed debris to enter and act as a medium.Alterations to the supply pipe network may have inadvertently created dead legs within the
system where legionella can thrive. Whatever the reason it is vital that the proper remedial
action is taken without delay to return the water supply system to a safe condition for the end
user.
7/30/2019 Legionella Control in Healthcare
34/72
34
An engineering approach to legionella control in Health Care Facilities
6.2 Daily chlorine dioxide readings
The benefits accruing from the installation of a chlorine dioxide dosing system have already
been discussed. Monitoring of the amount of chlorine dioxide present in the water supply
system is important for the following reasons
To ensure that the chlorine dosing plant is operating correctly To ensure the amount of chlorine in the system does not exceed statutory limits To check that outlying areas are receiving the benefits of added chlorine
Testing may be carried out manually by Facilities staff or automatically by sensing the
chlorine levels present at the cold water storage tank and relaying the results via the BMS to a
central computer for monitoring and recording. The advantage of manual testing is that
results can be monitored at several different locations throughout the cold water supply
system without the need to install chlorine sensors and cabling to the BMS. The distribution
of the chlorine dioxide in the system is also more accurately measured by manual testing as a
different test location can be chosen each day.
Chlorine dioxide test kit from Hach Technologies
http://www.hach.com/chlorine-dioxide-pocket-colorimeter-ii-test-kit/product?id=7640442961&callback=qs7/30/2019 Legionella Control in Healthcare
35/72
35
An engineering approach to legionella control in Health Care Facilities
Manual testing may be carried out by using the dilution method or a portable calorimeter
such as the Hach calorimeter above. The dilution method involves adding a re-agent and
free chlorine in liquid form to a water sample and determining the level of chlorine present by
the colour change in the sample.
This method is acceptable when checking that the chlorine dioxide plant is operating
correctly, but does not give detailed enough analysis to determine whether or not the correct
level of chlorine is being maintained throughout the system. The calorimeter on the other
hand is very accurate and will provide readings down to one hundredth of a millilitre.
The daily chlorine dioxide test begins with taking two ten millilitre samples of cold water
from the appropriate sentinel taps. The sentinel taps chosen should be the nearest and furthest
available cold outlets from the water storage tank. The calorimeter works by comparing the
levels of chlorine dioxide in one sample to the levels found in any previous sample. For this
reason the first sample taken is only used to zero the calorimeter so that the machine
compares the following real sample to a reading of zero chlorine and not to some
previously taken sample reading which may still be present in the calorimeter memory. The
second sample taken is prepared for testing by adding a chlorine re-agent to it and then a
sachet of free chlorine powder. The sample is agitated by shaking gently and is then placed in
the calorimeter which produces a very accurate chlorine dioxide measurement by passing a
beam of light through it. For chlorine dioxide to continue to be effective as a biocide in a
water distribution system, the level must be kept above 0.1 ppm. However levels must not
exceed 0.5 ppm which is the maximum allowable level for safe drinking water. Levels of
chlorine dioxide outside these parameters will necessitate adjustment of the central dosing
plant. Daily chlorine dioxide measurement is a time consuming and labour intensive
operation but should be seen as a vital component in any legionella prevention programme.
As with other testing, accurate records of chlorine dioxide levels must be kept and made
available for review on demand by relevant authorities.
7/30/2019 Legionella Control in Healthcare
36/72
36
An engineering approach to legionella control in Health Care Facilities
6.3 Monthly hot/cold water temperature testing
Monitoring the temperature of the hot and cold water supply is a good way to check whether
or not favourable conditions exist in the supply system for the growth of legionella. The
bacteria is inactive and cannot form colonies in water at temperatures under 20C.
Temperatures over 60C will quickly kill the bacteria. Legionella thrives best at water
temperatures around 35C and it is at this temperature that water systems may become
rapidly infected. A monthly temperature testing regime will quickly identify any areas where
optimum hot and cold water temperatures are not being maintained and remedial action can
then be taken. Temperature checks are carried out at sentinel hot and cold outlets. This
involves taking a temperature reading at the nearest and furthest hot and cold outlet from the
supply calorifier or cold water storage tank. The HPSC guidelines are as follows
Sentinel cold outlets must reach a temperature of below 20C within two minutes ofswitching on
Sentinel hot outlets must reach a temperature of over 50C within one minute ofswitching on
Temperature readings within these parameters indicate that there is no part of the hot and
cold water supply system where favourable conditions are being provided for the growth of
the legionella bacteria. Temperatures outside of these parameters should act as an alarm
signal that the water supply system may be vulnerable and a review of the supply network is
indicated. Possible reasons for temperature readings outside the accepted parameters could
include
Poorly insulated cold water storage tanks which may allow water temperatures in thetank to rise rapidly, especially during the summer months
Inadequately insulated or un-insulated hot water supply pipes suffering from highheat loss on route to the hot water outlet
7/30/2019 Legionella Control in Healthcare
37/72
37
An engineering approach to legionella control in Health Care Facilities
Poorly insulated cold water supply pipes suffering heat gains from nearby hot supplypipes or while passing through heated ceiling voids
Calorifier set point too low to maintain the water in the hot supply pipe at over 55C Poor plumbing practice leading to a crossover between the hot and cold supplies or
between the hot and hot return supplies
Poorly maintained hot return pumps failing to keep the water circulating in the supplypipework during periods of low load
As with all testing regimes, accurate records of temperature checks must be maintained.
These should be reviewed regularly and any necessary remedial action undertaken.
7. Interaction with other stakeholders
7.1 Medical staff education
In a health care facility it is all too easy for the various professions to adopt a blinkered
approach to their responsibilities around legionella control. The building services engineer
may be diligently implementing the Hospitals legionella prevention programme from an
engineering point of view but if he is doing so in isolation from the other professional
disciplines, then the control programme is not complete. It is vital that the engineer be in
regular formal and informal contact with all of the other stakeholders in the Hospital to
ensure that everyone is taking a co-ordinated approach to legionella control and prevention.
The medical staff and especially the nursing staff will already have a thorough knowledge of
the legionella bacteria from their medical training. They will know the risks associated with
the water supply system and how the bacteria enters the human body. Because they are in
constant contact with the hospital patients and will regularly assist many of them with
showering and bathing, they are a valuable asset right at the most dangerous interface where a
potentially vulnerable patient and a potentially infected water supply come together. It is vital
7/30/2019 Legionella Control in Healthcare
38/72
38
An engineering approach to legionella control in Health Care Facilities
that the medical staff think legionella prevention all the time. A good induction programme
will have a section on legionella prevention so that the Nurse or Doctor is aware before they
even take up employment that the Hospital or other health care facility takes legionella
prevention very seriously. Practical tasks that any nurse on the ward can carry out to aid the
fight against legionella include
Running the shower through one cycle before allowing the patient to use it Screening the patients so that potentially vulnerable people are given a pre-prepared
bath rather than being allowed to shower
Informing the Patients on a one to one basis of the risks associated with legionellaand what the Hospital does to control the bacteria
Liaise with the building services engineer on infrequently used or obsolete wateroutlets
7.2 Household/Catering staff flushing regimes
Household and Catering staff can play an important role in legionella prevention by ensuring
that infrequently used water outlets are flushed on a weekly basis.
This may seem to be a task which should be limited to the household staff on the hospital
ward but most hospital wards also have pantrys where the catering staff work and new
HACCP guidelines now state that catering sluice facilities must be separate from household
ones which usually means a separate sluice room which is under the control of the catering
staff.
The household and catering staff have two important roles in legionella prevention
1. To flush infrequently used water outlets2. To pass information to the building services engineer which may allow disused outlets
to be de-commissioned
7/30/2019 Legionella Control in Healthcare
39/72
39
An engineering approach to legionella control in Health Care Facilities
1. Both the household and catering staff are ideally placed to implement a flushingregime at ward or office block level. They have an intimate knowledge of all parts of
the building that they are responsible for cleaning. They will often build up a
relationship with the patients on the wards and will always know in advance if an
ensuite room is vacant or planned to be vacant. Some hospital wards close during
certain parts of the year due to decreased demand or budgetary constraints but thehousehold staff still remain on duty and are then even more important to the legionella
prevention programme. Any flushing regime implemented must be a formal
arrangement agreed with all of the relevant staff and implemented throughout the
organisation. Vulnerable areas left out of the flushing regime will render the rest of
the exercise useless as legionella colonies flourishing in neglected areas will
inevitably spread to the rest of the system through the distribution pipework.
A flushing sheet should be prepared by the building services engineer and distributed
to the household and catering staff at ward level by their managers. The flushing sheet
should have clear instructions on how to flush an outlet and should stress the
importance of using personal protective equipment during the flushing exercise.
Staff then fill in the forms weekly, noting what outlets were flushed and return them
to the manager who forwards them on to the building services engineer for review and
filing.
2. Household and catering staff will have a good idea from their flushing exercise ofwhich outlets are used infrequently and may discover outlets within their area of
responsibility which are never used at all. It is a good idea to leave space on the
flushing sheet where staff can note such outlets so that the engineer can assess
whether or not to remove them from service entirely so as to avoid dead legs where
legionella could flourish. When such action is taken and credited back to the staff
member who originally identified the outlet, this acts an encouragement and makes
the staff members feel that they are an important link in the legionella control
programme.
7/30/2019 Legionella Control in Healthcare
40/72
40
An engineering approach to legionella control in Health Care Facilities
7.3 Circulation of information/test results
The infection control committee of a hospital is usually the body tasked with implementing
and monitoring the legionella prevention programme. The committee will include
representatives from all disciplines within the hospital including a building services engineer
and hopefully a microbiologist. It is to this committee that the building services engineer will
initially report any legionella test results and on-going developments in the control
programme. However it is important that information around legionella be circulated as
widely as possible so that all staff members are encouraged to play their part in the on-going
fight against the bacteria. An open and honest dialogue between all staff members in relation
to legionella encourages inclusion and the feeling of ownership by individual staff members
of the legionella prevention programme.
7/30/2019 Legionella Control in Healthcare
41/72
41
An engineering approach to legionella control in Health Care Facilities
8. Case studiesIntroduction:
For my case studies I have chosen to examine the existing situations
pertaining to two hospitals, namely Basildon University Hospital near London and St
Patricks University Hospital in Dublin.
I chose Basildon University Hospital for the following reasons
It is situated in a neighbouring Country with similar legislative requirementspertaining to legionella control as Ireland
It has suffered fatalities which were directly linked to legionella It has suffered recent legionella fatalities-August 2011- The Basildon area was topical at the time of writing as the authorities were engaged in
evicting Irish traveller families from a long established but illegal encampment at
Dale Farm.
I chose St Patricks University Hospital because I work there in the Facilities Department as
assistant foreman and I am directly and intimately involved in the Hospitals legionella
control programme. I report to the facilities Manager, Eamonn O Reilly who is the designated
Responsible person for legionella prevention within the Hospital.
7/30/2019 Legionella Control in Healthcare
42/72
42
An engineering approach to legionella control in Health Care Facilities
8.1Basildon University Hospital
Basildon University Hospital is a large NHS Trust hospital with approximately 800 beds. It is
situated in Essex in England and is 25 miles east of London. It provides multi-disciplinary
care to the surrounding community including accident and emergency, cardiology, oncology
and general surgery departments. It is on a large site and consists of several interconnected
buildings. The hospital has an unenviable association with the legionella bacteria including
The death of a Patient who contracted legionellosis whilst being treated in the hospitalin August 2011
Three cases of legionella infection in patients in 2010 which were attributed to thehospital. One patient died and the other two responded to treatment
Three deaths at the hospital in the last nine years were found to be from legionellosiscontracted by patients during their time in the hospital
A fine of 25,000 was imposed on the hospital in connection with the death of a malepatient who contracted legionellosis in 2002
Legionella infection was linked to the deaths of two patients at the hospital in 2007and 2010 but inquest results on these have not been finalised to date.
The Hospital has had very negative media coverage arising from the various outbreaks of
legionella infection on the site. It has also been criticised over the higher than normal
mortality rate in its accident and emergency department. An unannounced inspection by
inspectors from the Care Quality Commission found unacceptable levels of hygiene and
patient care at the unit.
Given the amount of negative media exposure endured by the hospital over the years, it
would not be unusual if Management personnel there adopted a bunker mentality when it
came to disseminating information for public consumption but in any case there is very little
useful information available concerning the engineering methods employed by the hospital to
try to combat the level of legionella present in its water distribution systems.
7/30/2019 Legionella Control in Healthcare
43/72
43
An engineering approach to legionella control in Health Care Facilities
In an effort to obtain an overview of the hospitals legionella control strategy, I wrote to the
National Health Trust involved and also directly to the Facilities Manager at the hospital. A
copy of that letter is included in the appendices to this document. By the submission date for
my dissertation, I had not unfortunately had any reply from Basildon Hospital Trust or from
the Facilities Manager at Basildon Hospital. However an online news item may give some
idea of the steps that have been taken by the Hospital. A spokesperson told BBC News thatthe Hospital has spent two million pounds sterling on remedial works to the plumbing system
in the Hospital since the first incidence of legionella infection was discovered in 2002. The
spokesperson added that the Hospital has a strict regime of chemical dosing of the water
system in place and also carries out thermal disinfections of the water supply system. Finally
the spokesperson said that a comprehensive monitoring procedure for legionella control is in
place.
I would make the following observations about the Hospital statement.
Two million pounds is a very substantial sum of money to spend on remedial works toa plumbing system. I would be interested to know how the decision was made to
spend this money and how it was decided what works to carry out. The first step
should have been to have an independent legionella risk assessment carried out for the
entire site. This would have highlighted the areas and the services that were most at
risk of infection and allowed the Hospital management to target the available funds to
where the biggest payback was achievable.
Chemical dosing of the water supply system is a useful tool in legionella control butshould not be considered as a magic bullet. Adding chlorine in some form to the water
supply network at continual low concentrations kills the biofilm which harbours the
legionella bacteria and prevents its re-growth. Chemical dosing should be considered
to be a backup to good system management but never a substitute for it.
7/30/2019 Legionella Control in Healthcare
44/72
44
An engineering approach to legionella control in Health Care Facilities
Thermal treatment of the hot water supply system is a very labour intensive task andshould not be used as part of a regular maintenance programme. Thermal treatment is
useful following a positive legionella test result as it allows the system pipework to be
quickly purged of any remaining bacteria. The results are temporary however and if
the underlying reasons for the initial infection are not addressed, the system will be
rapidly re-infected. Thermal treatment requires the cooperation of a large number ofstaff to ensure that patients are not put at risk of scalding as the water in the calorifier
is raised to 80C before being released at this elevated temperature to the various
outlets being treated.
Which monitoring procedures are in place? and does this monitoring include thefollowing
1. Daily chlorine concentration measurements2.
Hot and cold water temperature checks
3. Regular independent testing of water samples Is a flushing regime in place in the Hospital for seldom used water outlets? A properly
run flushing regime implemented on the ground by staff who know the occupancy
patterns for a given area is very effective in preventing favourable breeding conditions
for the legionella bacteria. It also allows staff to buy into the idea of legionella
prevention in a practical way
7/30/2019 Legionella Control in Healthcare
45/72
45
An engineering approach to legionella control in Health Care Facilities
8.2 St Patricks University Hospital
St Patricks University Hospital is one of the leading psychiatric hospitals in Ireland. It can
accommodate approximately 300 Patients. It is the oldest purpose built psychiatric hospital in
Europe. The original building which still stands today was willed to the people of Dublin by
Jonathan Swift for use as a psychiatric hospital and it has been in continuous use as such
since the year 1745. The Hospital campus has developed in a piecemeal fashion over the
intervening years so that today accommodation is spread across several different buildings
both large and small, with each having its own hot and cold water services.
St Patricks University Hospital has never had a confirmed or to my Knowledge, suspected-
case of legionellosis. However, in 2008, higher than acceptable levels of the legionella
bacteria were found to be present in water samples when sent for analysis. Under present
guidelines, levels of bacteria exceeding 1000 cfu necessitate remedial action to be undertaken
and such levels were found to be present in a sample from one ward area. At the time, the
facilities department dealt with the problem by thermally treating the hot water supply to the
affected ward and chlorinating the cold water supply. This purged the system of the bacteria
and subsequent tests came back negative for legionella. Following this incident, an internal
review of systems for the control of legionella was instigated which resulted in the
appointment of an external expert to carry out a full risk assessment of all the hot and cold
water services in the Hospital and the systems in place for controlling and monitoring the
legionella bacteria.
Mr Bill Harley is an independent water services engineer from Scotland. He has worked
extensively with the NHS in Britain and Northern Ireland on legionella control for hot and
cold water systems. He is a Director of the CADHAM Consultancy Group and is engaged in
legionella control programmes with several health care facilities in Ireland. He carried out a
full legionella risk assessment in St Patricks University Hospital during the summer of 2008.
This involved several site visits to inspect the plant and to review the existing control
measures and documentation. The risk assessment discovered many failings and
7/30/2019 Legionella Control in Healthcare
46/72
46
An engineering approach to legionella control in Health Care Facilities
short-comings in the legionella control programme in place in the Hospital at that time but
also provided a platform on which the Hospital could build a co-ordinated programme going
forward. The Hospital now has a system for monitoring and controlling the bacteria that
complies with best practice in the industry and more importantly complies with the law as it
stands in Ireland. The legionella monitoring and control programme now in place in the
Hospital has many elements
The Building Management System BMS- plays a very important role in legionellacontrol. The BMS is a computer software programme which allows the user to
monitor and adjust various aspects of a building such as heating, ventilation and hot
water systems. The St Patricks Hospital BMS was already monitoring the flow
temperatures of the hot water systems. Following the risk assessment, temperature
stats were fitted to the return pipework also. For legionella control, it is important to
maintain the hot water temperature in the calorifier at a minimum of 60C and the
temperature of the water returning to the calorifier should not fall below 50C. If the
flow or return temperatures fall below their pre-set levels, an alarm will activate on
the BMS and the facilities department will investigate the reason for it. The reason
could just be heavy usage of the hot water available at certain times of the day and
the temperature will recover quickly. However if the reason was a pump or boiler
failure and the BMS was not monitoring the system, then water could lie in the pipe
work at a temperature that would facilitate rapid growth of the legionella bacteria.
This water could then potentially be delivered to a shower outlet being used by a
patient with a compromised immune system. An important aspect of the building
management system recognised by Bill Harley following his recently completed bi-
annual review was the ability to store historical water temperature data so that this
could be reviewed on a regular basis. This allows an assessment to be made as to
whether hot water temperatures are likely to be falling below minimum levels for
periods of time long enough to encourage bacteria growth. The Hospital has had thisfacility added to the BMS by the system management company.
7/30/2019 Legionella Control in Healthcare
47/72
47
An engineering approach to legionella control in Health Care Facilities
The risk assessment highlighted many shortcomings in the cold water storagefacilities in the Hospital. Many storage tanks were old and un-insulated; some were
not even covered. The Hospital undertook a full review of all the cold water storage
tanks and implemented a remediation plan. All water storage tanks were fitted with
water meters to make sure they were sized properly. This is important as only twenty
four hours of stored water should be available in a cold water storage tank to allowfor interruption of supply. Any more than this means that there is not enough
throughput of water and during a hot summer day this excess water is rapidly heating
up to a temperature that would favour the growth of the legionella bacteria. Sizing the
water storage capacity properly allowed the Hospital to consolidate three separate
storage tanks into one and the two older tanks were then disconnected and taken out
of use. All modern water storage tanks have inbuilt insulation and hinged access
covers for maintenance and
Recommended