RAINWATER Guidelines for Installing A Rainwater Collection and Utilization System

CONTRIBUTIONS: Grateful acknowledgment is made of the assistance provided to the successful compilation of this guideline by the following: Architect and Special Projects Department Kuala Lumpur City Hall Local Government Department Ministry of Housing and Local Government Drainage and Irrigation Department Ministry of Natural Resources and Environment Vector Borne Disease Control Division Ministry of Health Water Resources Management Division National Hydraulic Research Institute of Malaysia (NAHRIM) Association of Consulting Engineer’s Malaysia (ACEM) Institute of Engineer’s Malaysia (IEM) Association of Architect Malaysia Real Estate and Housing Developers Association (REDHA) Perbadanan Kemajuan Negeri Selangor

Majlis Perbandaran Pulau Pinang Majlis Perbandaran Sandakan Syarikat Bekalan Air Selangor (SYABAS) Persatuan Pengurusan Kompleks Malaysia

THE COMMITTEE FOR THE GUIDELINES FOR RAINWATER COLLECTION AND UTILIZATION SYSTEM

Advisor Y.B.Dato’ Azmi Bin Khalid Timbalan Menteri II Kementerian Perumahan Dan Kerajaan Tempatan

Technical Advisor Encik Hassan bin Haji Hamzah

Pengarah Jabatan Arkitek dan Projek Khas Dewan Bandaraya Kuala Lumpur

Chairman Ir.Hooi Yoke Meng

Timbalan Pengarah Jabatan Arkitek dan Projek Khas Dewan Bandaraya Kuala Lumpur

Committee Ir.Fong Tian Yong Pengarah Unit Kawalan Bangunan Kementerian Perumahan dan Kerajaan Tempatan Encik Nordin bin Mohd Salleh Jabatan Kerajaan Tempatan Kementerian Perumahan dan Kerajaan Tempatan Encik Hew See Seng Jabatan Arkitek dan Projek Khas Dewan Bandaraya Kuala Lumpur Ir.Hj.Abdul Hamid bin Md.Kassim Bahagian Saliran Jabatan Pengairan dan Saliran Kementerian Pertanian Ir.Cheng Pek Siang Jabatan Pengairan dan Saliran (Wilayah Persekutuan) Kementerian Pertanian Encik Tee Sing Tiat Jabatan Pengairan dan Saliran (Wilayah Persekutuan) Kementerian Pertanian Encik K.Nantakumar Jabatan Saliran dan Pengurusan Sungai Dewan Bandaraya Kuala Lumpur

RAINWATER Guidelines for Installing A Rainwater Collection and Utilization System

INTRODUCTION

Wherever the country or city experiences a severe water shortage,is inclined to construct more

dams upstream.The development of giant dams upstream however devours vast tracts of forest

and the cost of such projects are enormous.Moreover the demand of water supply in urban

areas is likely to increase due to a rapid concentration of population and increase in industries.

The country is endowed with far more rainfall than the amount of water demand.Rainwater

harvesting could be and effective tool for helping to reduce the use of treated water and

provides a convenient buffer in times of emergency or a shortfall in public water supply.

Rainwater harvesting from rooftop catchments and cistern storage is not new.It has been an

important source of water supply for domestic purposes in many rural areas in the past.

The need to promote rainwater collection and utilization can lead to the comprehensive

resolution of water resources problems and the environmental problems in urban areas.

The proposal to build tens of thousands of “mini dams” (rainwater tanks) in urban areas instead

of continuing to build giant dams upstream not only contribute to treated water conservation

but also helps to control urban floods by storing rainwater from roofs and the ground

surface.The stored water can be used for non-drinking purposes and as a back-up water supply.

RAINWATER Guidelines for Installing A Rainwater Collection and Utilization System

CONTENTS PAGE

Acknowledgements Introduction 1.1 PURPOSE OF GUIDELINES 1 1.2 SCOPE THE GUIDELINES 1, 2 1.3 HOW TO USE THE GUIDELINES 2 2. ELEMENTS OF RAINWATER COLLECTION

AND UTILIZATION SYSTEM 2.1 Collection Area 4 2.2 Conveyance Area 4 2.3 Storage Facility 4 2.4 Distribution System 4

3. QUALITY OF RAINWATER & USAGE OF RAINWATER 3.1 General 6 3.2 Rainwater and Roof Collection 6 3.3 Recommended Usage of Rainwater 6

4. TECHNOLOGIES FOR RAINWATER COLLECTION AND UTILIZATION 4.1 Collection rainwater from Roof 8 4.2 Eliminating Contaminated first Flash Rainwater 10 4.3 Draining Excess Rainwater in Heavy Rain 10 Protecting Rainwater Utilization Facilities from Heavy Rain 4.4 Intercepting Obstacles Using Filters, Strainers and Nets 12 4.5 Storing Rainwater in Tank 12, 14 4.6 Supplying Rainwater to Place of Use 16 4.7 Using Treated Water in Times of Shortage 18 4.8 Prevention of Mosquito Breeding 18

CONTENTS PAGE

5. MULTI-STOREYED BUILDING

5.1 Definition 20 5.2 Rainwater Collection and Utilization 20 5.3 Roof Catchments 20 5.4 Collection Rainwater 20 5.5 Rainwater Storage Tank/Facility 20 5.6 Usage of Rainwater 22 5.7 Eliminating Contaminated First Flash Rainwater 22 5.8 Rainwater for Toilet Flushing 22 5.9 Material of Elevated Rainwater Tank 22 5.10 Using Treated Water in Time of Rainwater Shortage 22 5.11 Grit Chamber & Sedimentation Tank 24 5.12 Technical Points to be considered for 24

Large Rainwater Storage Tank

6. MAINTENANCE OF RAINWATER COLLECTION AND UTILIZATION 6.1 Catchments Area 26 6.2 Sedimentation Tank 26 6.3 Filter/Screen 26 6.4 Rainwater Storage Tank 26 6.5 Rainwater Supply Equipment 26

7. CREATIVE DESIGN OF RAINWATER COLLECTION AND UTILIZATION FACILITIES 27 7.1 General 7.2 Creative Design APPENDIX A. EXAMPLES OF CREATIVE DESIGNS OF RAINWATER STORAGE FACILITY 1. Rainwater Tank Using Columns or brick Piers 28, 29 2. Rainwater Tank Using Partition Wall Fencing 30 3. Rainwater Tank as an Landscape Element 31 4. Rainwater Tank as an Architectural Feature 32

CONTENTS PAGE

B. TYPICAL EXAMPLES OF RAINWATER

COLLECTION AND UTILIZATION 1. Tank at First Level with Gravity Supply 33 2. Tank on Ground Level .Pumping & 34 Roof Tank Gravity Supply 3. Tank Underground, Pumping & 35 Roof Tank Gravity Supply

TABLES 1. Average PH of Rainwater in Kuala Lumpur 3

And Petaling Jaya for 1998 2. Recommended Storage Capacity 13 3. Plan to Maintain Rainwater Utilization Facilities 25

FIGURES

1. Elements of a Rainwater Collection and Utilization System 3 2. Device to Cut First Flash Rainwater (I)-Using Separation Pipe 7 3. Device to Cut First Flash Rainwater (II)-Using Separation Tank 9 4. Device to Deal with Heavy Flash Rainwater 9 5. Net at Roof Drain 11 6. Net at Gutter 11 7. Filter in Rainwater Down pipe 11 8. Strainer in Rainwater Down pipe 11 9. Details at Storage Tank 13 10. Roof Top/Tank (Gravity Supply) 15 11. Underground Tank (Pumped Supply) 15 12. Ground Level Tank (Pumped Supply) 15 13. Prevention of Mosquito Breeding: Using Insert Proof Net 17 14. Separate Down pipe for Rainwater Collection and Discharge from Cooling Tower and Elevated Tank 17 15. Water Supply from Elevated Rainwater Tank 19 16. Rainwater Tank with Electrode Rod Control 21 17. Grit Chamber 21 18. Ground Level Sedimentation Tank 23 19. Sedimentation Tank Incorporated in Rainwater Storage Tank 23

1.0 RAINWATER COLLECTION AND UTILIZATION

1.1 PURPOSE OF GUIDELINES

The guideline for rainwater collection and utilization has been prepared to document some of the ways in which rainwater can be collected from roofs of the buildings and the practical utilization of the rainwater. The Guidelines:-

• Is intended as an “ideas manual” for references for those who wants to install a rainwater collection and utilization system.

• Is intended to provide some information on the quality of rainwater,the

rationale behind the techniques of rainwater collection and utilization system suggested.

• Is aimed at encouraging the owner to think and adopt wherever possible

appropriate innovative alternatives which offer real advantages (cheaper to the owner, more functional, aesthetically pleasing) and adaptable to his needs.

1.2 SCOPE OF THE GUIDELINES

The Guideline is divided into the following sections and appendices:-

• Section Two This section briefly explains the elements or components of the rainwater collection and utilization system. • Section Three This section provides some information of the quality of rainwater and recommended usage of rainwater. • Section Four This section explains the technologies for rainwater collection and utilization system i.e. system to collect, store and use. It provides a selection of alternative design elements which maybe appropriate in a given context.It also include the menthod of preventing the breeding of mosquito.

• Section Five This section outlines some principles of installing a rainwater collection and utilization for multi-storeyed buildings that differs from the system for singles/double terrace or stand-alone buildings. • Section Six This section gives a recommended maintenance plan of the rainwater collection and utilization system for the use of clean rainwater. The scopes described are likely to meet the needs in terrace houses, bungalows, multi-storeyed buildings in housing complexes, commercial buildings and school. • Section Seven

This section makes suggestion that rainwater storage facility may not necessarily be ready-made tanks. Storage facility can be designed with the greatest potential as pieces of architecture, landscape and aesthetically to blend with the surrounding environment. • Appendix A

This appendix explores and gives some creative designs of rainwater storage facility in place of storage tank that is aesthetically pleasing. -some food for thought. • Appendix B This Appendix provides examples of typical rainwater collection and utilization system for terrace house and bungalows.

1.3 HOW TO USE THE GUIDELINES

The guidelines set out recommendations for the general principles, designs, layout and installation of a rainwater collection utilization system. Although the emphasis in on housing and domestic uses,the principles and designs for other buildings are similar.For this purpose,recommendations set up for ‘large installation system’is refered to multi-storey building or where rainwater usage is big and ‘small installation’ is refered to single /double storey terrace or stand alone building or where the rainwater usage is small.

The system consists of a ‘collection system’and the ‘utilization system’.If there is constraints in budget,space requirement ,difficulty in renovation of pipes in existing buildings to supply rainwater for toilet flushing,the owner can install only a collection system,with a tap outlet attached to the rainwater storage tank and supply to places of use can be from a bucket or watering can be directly or through a hose connected to it. This uses the recommendations to suit the individual needs.

2.0 ELEMENTS OF THE RAINWATER COLLECTION AND

UTILIZATION SYSTEM

The main components and elements in the rainwater collection system are:- 2.1 The Collection Area

1. Individual rooftop of house or building. 2. Communal catchments -directly from the sky - surface run-off from large paved area.

2.2 Conveyance System 1. Series of gutters that carry the rainwater from the collection area to the

cistern / storage tank.

2.3 Storage Facility 1. Constructed as part of a house or building.

2. Constructed / installed separately on the ground or under the ground. 3. Storage tanks or storage facility of creative design.

2.4 The Distribution System

1. The plumbing system (including pumps if necessary) supplying rainwater to the place of use.

Basic element of a rainwater collection and utilization system with storage facility is shown in Fig.1.

3.0 QUALITY OF RAINWATER

3.1 GENERAL

1. The quality of rainwater depends on the air quality. Rain washes off suspended particles in the air while falling. Rain in urban areas contains harmful substances such as sulphur dioxide and nitrogen oxides discharges from cars and factories, and acid rain is the result of these in the air.

2. The parameter ‘pH’ is used for measure of the acidity in rainwater.(pH 7 =

neutral,and lower the number,the more acidic the water)

3. From record of rain stations,collected in Kuala Lumpur and Petaling Jaya for 1998, the pH value of the rain is between 4.4 to 4.8.(table 1)

3.2 RAINWATER AND ROOF COLLECTION

1. The quality of rainwater collected from the roof of buildings depends on the condition of the roof. Dirt, soot, leaves and excreta of cats and birds are deposited on or attached to roofs causing contamination.Contamination is especially heavy with the first raindrops after a long dry spell.

2. The first flush rainwater must be eliminated from the catchments before it is

collected. (Refer to 4.2).

3. The Interim National Water Quality Standards For Malaysia and Water Quality Category and uses (Refer to 4.3 and 4.4).

3.3 RECOMMENDED USAGE OF RAINWATER

1. The quality of rainwater is determined by the collecting source.Rainwater collected from roofs of buildings should not be used for drinking and cooking purposes.

2. Rainwater collected should therefore be used for the following purposes:-

i) Flushing toilets ii) Watering plants iii) Washing vehicles iv) General cleaning

4.0 TECHNOLOGIES FOR RAINWATER UTILIZATION

• System to collect,store and use, The technology to operate a rainwater collection and utilization system is made of the following functional techniques:-

1. Collecting rainwater from roof. 2. Cutting off contaminated rainwater when rain starts. 3. Draining excess rainwater in heavy rain. 4. Storing rainwater in tanks. 5. Supplying rain water to the place of use.

6. Using treated water in times of shortage.

• This chapter mainly deals with crucial point of each functional technique in

rainwater utilization for:-

1. Bungalows 2. Terrace house

3. Multi-Storeyed building

4.1 COLLECTING RAINWATER FROM ROOF 4.1.1 Roof

The roof of buildings resources for rainwater catchments.Ensure the largest possible area for rainwater catchments.

4.1.2 Roof Surfaces

Roof surfaces should be chemically inert materials,such as concrete tiles,metal deck….in order to avoid adverse effects on water quality.

4.1.3 Rainwater Down-Pipe

Down pipes should be of chemically inert materials such as UPVC, galvanized iron… in order to avoid adverse effects on water quality.

4.1.4 Gutters

Gutters should be of chemically inert materials such as UPVC, galvanized iron… in order to avoid adverse effects on water quality.

4.2 ELIMINATING CONTAMINATED FIRST FLUSH RAINWATER 4.2.1 General

1. Rain washes off suspended particles in the air while falling. 2. Rains in urban areas contain harmful substances such as sulphur dioxide and

nitrogen oxides emitted from cars and factories.

3. Dirt and soot containing harmful substances deposited on or attached to roofs causing contamination.

4. Contamination is especially heavy with the first raindrops after a long dry

spell.

5. Thus first flush rainwater for 5 to 10 minutes must be eliminated from catchments.

4.2.2 Device to separate first flush rainwater.

1. Install a small first flush separation tank at the down pipe as shown in Fig.3. 2. Rainwater flows into the small tank first and when the tank is full,a float valve

installed in the small tank closes the inlet of the tank and the running rainwater flows into the main rainwater storage tank.

3. Empty the first flush separation tank before the next rainfall.

4. Another method to separate first flush rainwater using separation pipe is

shown in Fig.2. 4.3 DRAINING EXCESS RAINWATER IN HEAVY RAIN 4.3.1 General

1. When the great amount of rainwater gushes into a storage tank through a rainwater collecting pipe in heavy rain,soil and sand accumulated at the bottom are stirred up and this can cause equipment trouble.

2. The excess water during heavy rain will also overflow. 4.3.2 Protecting rainwater utilization facilities during heavy rain.(Fig.4)

1. An overflow pipe shall be installed in the tank. 2. The diameter of the overflow pipe should be larger than that of the rainwater

inlet pipe.

3. A short pipe for relieving the pressure of the collecting pipe should be attached to the vertical part of the collecting pipe to prevent abnormal pressure from being produced inside.

4.4 INTERCEPTING OBSTACLES USING FILTERS STRAINERS,AND NETS.

4.4.1 General 1. Leaves, dirt or sand gathering around roof or gutter pollute rainwater.

2. Frequent cleaning is not practical for this uppermost part of the house or

Building.

4.4.2 Cartridge-Filters, Strainer And Nets

To prevent leaves, dirt or sand coming together into the downpipe and into the rainwater tank:- 1. Install a ready-made cartridge filter or strainer just before the rainwater enters the

storage tank. 2. Cartridge filters should be replaced regularly.

3. Strainer should be made of rust proof material to prevent the deterioration of water

quality and be designed to be easily removable.

4. Ordinary net mesh or stainless mesh can be used at roof drain and gutter.(Fig.5 & Fig.6)

5. A net or screen mesh of 2-3 to 10mm is suitable.

6. A strainer or a cartridge filter installed just before the rainwater enters the storage

tank makes removal of obstacles easier.

4.5 STORING RAINWATER IN TANKS 4.5.1 Storage Tank

Any vessel or container used as a rainwater storage tank shall comply with following conditions:- 1. No leakage 2. Made of material that contains no ingredients that could dissolve in rainwater,thus

contaminating it and that is sunproof to prevent algae from growing. 3. It must have a lid to prevent dirt and vapourization and is designed so that the inside

can be easily cleaned.

4.5.2 Material of Storage Tank.

1. Ready-made rainwater tanks in markets can be used. 2. Tank material can be hot dipped galvanized steel,stainless steel,glassfibre

reinforced plastic,reinforced concrete and polyethylene.(Refer to Table 2)

4.5.3 Design Of Storage Tank.(Fig.9) All rainwater tank should include as an minimum requirement :-

1. A solid secure cover 2. A overflow pipe larger in diameter than the incoming rainwater supply pipe.

3. A scour pipe and valve for drainage.

4. An extraction system e.g taps or pumps.

5. A device to indicate the water level in the tank (optional).

4.5.4 Recommended Storage Capacity.

1. Recommended minimum storage capacity for building category given in Table 2. 2. The minimum storage capacity is based on use of rainwater usage for toilet

flushing, watering plants, washing vehicles and general cleaning.

3. It is based on the location having rain once every 4 days on the average.

4. Existing structures may have difficult to ensure a place for large rainwater storage

tank.

5. A larger storage tank is not necessarily beneficial as shortage of rainwater can be supplemented by treated water.

4.6 SUPPLYING RAINWATER TO PLACE OF USE

4.6.1 General

The system of supplying rainwater to place of use depends on the place of installation of tank or storage facility. For tanks installed at:-

4.6.2 Rooftops (Balconies or Roof-Terrace) Rainwater storage tanks / facility installed either in roof tops (including balconies or roof-terrace),it is possible to supply the water to toilets by gravity.(Fig.10)

4.6.3 Under The Roof (Above the Ceiling).

The simple purpose of collecting and utilizing rainwater is to install the storage facility/tank under the roof and it is possible to supply water to lower level/floors by gravity.There maybe a restriction on the tank size due to space.The structure of the building needs to be checked to ensure that it is sufficiently adequate to take the weight of the water.

4.6.4 Ground Level And Underground Level

It the storage tank is installed to the ground level,in the garden or underground,it is necessary to pump water to supply it to upper levels/floors.(Fig.11 & 12)

4.6.5 Rainwater Plumbing System

1. The rainwater pipe supplying to place of use should be a separate piping system from the treated water piping system to prevent contamination of the treated water.

2. Paint the rainwater supply pipe for easy identification.

4.6.6 Pumps

1. For small installations, pneumatic pumps may suffice.However for large installations centrifugal pumps or end section pumps may be used.

2. Consult an experienced plumber or an engineer for advice if in doubt before

installing the pumping system. (Refer to Table 3)

4.7 USING TREATED WATER IN TIMES OF RAINWATER SHORTAGE

4.7.1 General

When rainwater is used for flushing, toilets become unusable when the rainwater tank runs out of water.It is necessary to use treated water from the treated water supply system, when there is no rain.

4.8 PREVENTION OF MOSQUITO BREEDING

To prevent the breeding of mosquitoes, the following are recommended:-

1. The rainwater is recommended to be used regularly and replenished often as mosquito larvae will not hatch in tank if it is used regularly.

2. Use the rainwater instead of treated water wherever rainwater is available.

3. During period of dry weather, the rainwater tank will be empty,the remaining

stagnant water should be drained out completely.

4. If the rainwater is kept for several days,it is advisable to use ‘Abate-1-SG’ to prevent the breeding of mosquitoes.Recommended dosage shuld be 10gm ‘Abate-1-SG’ for every 90 litre of water.

5. The overflow pipe only has water running through it during rainfall and it can be a

route for mosquitoes to enter the rainwater storage tank.Putting a net over the outlet of and overflow pipe will prevent their invasion.(Fig.13)

5.0 MULTI-STOREY BUILDING

5.1 Definition

1. Multi-storey buildings refer to buildings other than single /double storey terrace building or bungalows.

2. Multi-storey buildings maybe an office-block,a commercial complex,an institutional building or a medium/high rise housing complex.

5.2 Rainwater Collection And Utilization

1. Generally the technology of rainwater collection and utilization is similar to single/double storey terrace house and bungalows.

2. Rainwater collection and utilization in these buildings usually have limited

catchment areas, storage places and storage capacity if no so designed for.

5.3 Roof Catchment 1. For flat-roof,check if there is a cooling tower or an elevated tank on the building

rooftop. 2. The cooling tower discharges salt-rich water into the rainwater downpipe and the

water drained from the elevated tank into the rainwater downpipe (if there is no separate drainage downpipe from the tank) is contaminated by cleaning chemicals.(Fig.14)

3. Ensure that during and after cleaning, the waste water from the cooling tower or

elevated water tank is drained through a separate drainage downpipe or else,the rainwater collected is not recommended for toilet flushing.

5.4 Collecting Rainwater

The simplest and the most reasonable method for collection of rainwater is from the bottom of a nearby rainwater downpipe into a storage tank installed where rainwater is used.

5.5 Rainwater Storage Tank / Facility

The rainwater storage tank / facility is normally installed on the ground, underground or under the floor of the lowest level because of its large facility.

5.6 Usage Of Rainwater For existing buildings, renovation of pipes and pipe system is not easy and costly, rainwater can be used for car washing,garbage collection area cleaning,and plant watering.

5.7 Eliminating Contaminated First Flash Rainwater

The storage facility in multi-storey building can store a large amount of rainwater,first flash rainwater represent only a small portion.In such installations,first flash rainwater can be left in the storage tank.

5.8 Rainwater For Toilet Flushing

1. Rainwater for toilet flushing is feasible for new buildings where the roof area,storage places,storage capacity and the rainfall plumbing system are designed for.

2. Rainwater is pumped from the rainwater tank on the ground /underground to an

elevated tank.

3. Rainwater is then supplied to toilet facility at each floor by an elevated rainwater tank by gravity.

4. A float valve or an electrode rod is installed to start or stop the pump when the level

in the rainwater tank at the ground or in the elevated rainwater tank falls below a certain point or when the level in the elevated tank is full.(Fig.16)

5. Install a pressure-reducing valve on the rainwater supply pipe if the water pressure

is too strong.

6. Fig.15 shows a typical water supply from an elevated rainwater tank.

5.9 Material Of Elevated Rainwater Tank The material and structure are basically the same as those for treated water.

5.10 Using Treated Water In Times Of Shortage

It is necessary to use treated water from the treated water supply in times of shortage of rainwater or when there is no rain.

5.11 Grit Chamber & sedimentation Tank (Optional) 1. For large rainwater tank,a grit chamber and a sedimental tank are often incorporated

into a rainwater storage system to remove soil and sand from rainwater. 2. They are designed to use only the clear layer at the top of the water by settling soil

and sand in the grit chamber and suspended particles in the sedimentation tank by gravity.

3. A grit chamber is installed before a sedimentation tank,is generally designed to

retain rainwater for 30 to 60 seconds.(Fig.17)

4. The storage time for suspended particles to settle slowly is generally 2 to 3 hours depending on the kind of suspended particles.

5. For a rainwater tank capacity less then 10 m3 only a sedimentation tank is required. Fig.18 shows a typical ground level sedimentation tank.

5.12 Technical Points to Be Considered For Large Rainwater Storage Tank 1. Prevention of trash from flowing into tanks, use screen. 2. Prevention of sediment diffusion, use grit chamber and sedimentation tank.

3. Prevention of pumping up sediment, use barrier wall.

4. Removal of sediment, use a drain pipe with valve at the bottom of tank, sloping the

bottom of the tank, catch pit and access.

5. Prevention of rainwater I heavy rain from gushing in and stirring sediment, have a bumper made of an artificial turf-like material just below the rainwater inlet.

Fig.19 shows a typical sedimentation tank incorporated in a rainwater tank.

6.0 MAINTENANCE OF THE RAINWATER UTILIZATION FACILITIES Maintenance of the rainwater utilization equipment is very important for the collection, storage and use of clean water. The following areas should be carried out during the periodic cleaning of the system.

6.1 Catchment area Trash and animal excreta in catchment area including roof must be cleaned off regularly to prevent downpipe clogging.

6.2 Sedimentation Tank

In the off-rainy season, sedimentation tanks should be cleaned completely.For ground level rainwater tanks, sediment is removed from the drain pipe at the bottom of the tank. (Fig.18)

6.3 Filter/Screen Sand and trash caught by filters/screen should be removed and cleaned regularly.

6.4 Rainwater Storage Tank

Inside check should be conducted when sediment is removed.The inside should be cleaned.Through maintenance of the catchment areas, sedimentation tank/filter/screen can reduce the frequency of inside cleaning.

6.5 Rainwater Supply Equipment Make sure that mechanical devices such as pumps are working normally by checking at least every three months.Other devices should undergo a check about every six month and maintained in the same way as treated water equipment. Table 3 : shows a recommended plan to maintain the Rainwater Utilization Facilities.

7.0 CREATIVE DESIGN OF RAINWATER STORAGE FACILITY 7.1 General

1. One of the difficult problems in promoting rainwater collecting and utilization at single / double storey terrace house is securing rainwater storage space for a large volume of rainwater.

2. In existing houses,buying a ready-made rainwater tank and place it in the gardens or

on the side of house entrance or the back often is objectionable to the owners as it is not aesthecally pleasing.

7.2 Creative Design

1. Rainwater storage facility can be designed (using architectural techniques) as a architectural feature or landscape feature aesthetically to blend with the surrounding environment.

2. Appendix ‘A’ gives some examples of creative designs of rainwater storage facility

in place of storage tank that is aesthetically pleasing.

3. These ideas are to encourage owners as well as architects to spawn new, practical, creative and innovative ideas in designing rainwater storage facility as a ‘work of art’.