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Rainwater Harvesting

In Alberta

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3 Year Research Project at University of Guelph

• What Rainwater Is • Permitted Rainwater Uses In Alberta

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• Rules And Regulations • Anatomy Of A Rainwater Harvesting System

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What Is Rainwater? Rain That Falls On The Roof Of A Single

Family Dwelling

What Rainwater Is Not.

Rain That Falls Anywhere Else

What Can You Use Rainwater For In Alberta?

• Toilet and Urinal Flushing

• Sub-surface Irrigation

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Codes

• Alberta Building Code

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• National Plumbing Code

National Plumbing Code

• Support for underground horizontal piping • Pipe trench backfill • Hydraulic load for roofs or paved surfaces • Hydraulic load on storm or combined building drains

or sewers • Connection of overflow from rainwater tank • Pipe system sizing and capacity • Permitted rainwater outlets • Thermal expansion • Backflow prevention

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Alberta Building Code

• Design data for selected locations in Alberta (conveyance pipe systems)

• Plumbing system and fixtures

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Standard - CSA

• B64 • Backflow Prevention

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Regulations

• Alberta Private Sewage Systems Standards And Practices • Sections 2.5, 4.2

• Tank installation, insulation, etc.

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• Alberta Occupational Health And Safety • Confined Spaces

Guidelines - CSA

• Installation requirements • Pumps • Separation between potable and non-potable

systems • System testing • Non-potable component marking • Water treatment

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B128

Guidelines – CSA (cont’d)

• B128 • Tanks

• Suitable for burial • Access • Pipe connections • Draining • Venting • Overflow

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Guidelines

• Stormwater Management Guidelines For The Province Of Alberta • On-site infiltration systems

• Alberta Guidelines For Residential Rainwater Harvesting Systems

• Canadian Guidelines For Domestic Reclaimed Water For Use In Toilet And Urinal Flushing

• Local Authority Having Jurisdiction • Local Health Authority

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Interested Government Departments

• Alberta Municipal Affairs • Alberta Environment and Sustainable

Resource Development • Alberta Health Services

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Rainwater Quality Codes, Standards And Guidelines

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•NONE

Anatomy Of A Rainwater Harvesting System

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• Catchment Area

• Conveyance Network

• Storage Tank(s) • Overflow And Stormwater Management

• Distribution System • Water Filtration And Treatment

• Potable Water Make-Up And Backflow Prevention

Catchment

width

1 mm of rain on 1 m2 of roof = 1 Litre 18

length

Conveyance Network

CATCHMENT AREA

EAVESTROUGH

DOWNSPOUT

DOWNSPOUT TO PIPE TRANSITION

STORAGE TANK

CONVEYANCE PIPE

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Conveyance System

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• Eavestrough • Slope toward storage tank

• Downspouts • Locate as close to storage tank as possible • Seal transition between downspouts and

conveyance pipe

• Conveyance Piping • PVC SDR35 – usually 4” Ø – size in accordance with

the building code and local regulations • Slope – 0.5% - 2% • Rated for UV exposure

Storage Tank

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Storage Tank Sizing & Placement

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Size

Location

Material • Water usage • Water demand • Volume of water to be stored • Catchment area • Rainfall pattern and volume • Conveyance system loss

• Space • Inside/Outside • Above ground/Underground • Downspout location(s) • Overflow location • Easements/Rights-of-way • Utilities • Access

Cost

• Concrete • Fiberglass • Plastic

• Tank • Plumbing • Electrical • Installation • Transportation • Permits

Weather • Drain for winter • Insulation

Suggested Tank Sizing

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Rainwater Demand (L/day)

Optimum Cistern Capacity (L) Roof Catchment Area (m2)

50 100 150 200 250 300 350

400

50 5,000 5,000 2,000 2,000 2,000 2,000 2,000 2,000

100 2,000 3,500 3,500 3,500 3,500 3,500 3,500 3,500

150 2,000 3,500 3,500 3,500 3,500 5,000 5,000 5,000

200 2,000 3,500 3,500 3,500 3,500 5,000 5,000 5,000

250 - 3,500 3,500 3,500 3,500 3,500 5,000 5,000

300 - 2,000 2,000 3,500 3,500 3,500 5,000 5,000

350 - 2,000 2,000 3,500 3,500 3,500 5,000 5,000

400 - 2,000 2,000 3,500 3,500 3,500 5,000 5,000

450 - 2,000 2,000 2,000 3,500 3,500 5,000 5,000

500 - - 2,000 2,000 3,500 3,500 5,000 5,000

Edmonton: 350mm annual rainfall

Overflow & Stormwater Management

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• A Rainfall Event May Provide More Water Than the Storage Tank Can Hold. Therefore the Excess Water Must be Disposed of in a Safe and Approved Manner

• How and Where Can the Water be Disposed Of?

• Applicable Codes and Regulations • Stormwater Management Guidelines • Type of Lot • Year Lot Was Developed • Current Stormwater Management Techniques

Above Ground Tank Overflow

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Discharge to grade

Storage Tank

Underground Tank Overflow

STORAGE TANK

Soak-Away Pit

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Storm Drain

Distribution System

• Moving The Water To The Desired Locations In A Safe And Approved Manner

• Distribution System Components

• Pump And Controls • Pressure Tank • Distribution Piping

Pumps Submersible

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Jet

Pressure Tanks

Jet Pump

Pump & Distribution System

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Calculating Pump Flow Rate

30 Adapted from Residential Water Systems: Goulds Pumps Technical Data, Water Products. 2007. ITT Corporation, White Plains, NY.

Indoor Fixtures Minimum Flow Rate

Toilet 2.7 LPM [0.7 GPM]

Urinal 2.7 LPM [0.7 GPM]

Outdoor Fixtures Minimum Flow Rate

Sub-surface irrigation system

Varies (consult Supplier/

Contractor)

Rainwater Pressure Piping

• 100 mm separation of potable & non-potable pipes

• Pipe and Outlet Markings: – Outlet label: graphic (see right) or text – Purple pipes (or stripe) – Pipe labeling: – Label must be 5mm height, repeated at

1.5m intervals for pipes

WARNING: NON-POTABLE WATER — DO NOT DRINK

AVERTISSEMENT : EAU NON-POTABLE — NE PAS BOIRE

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Rainwater Quality & Treatment

Pre-Storage Treatment: Filtration

Located in eavestroughs and downspouts 33

Pre-Storage Treatment: Diversion

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Pre-Storage Treatment: Sedimentation

Access risers

Overflow line

Pump outlet line

Rainwater inlet line

Low-level make-up line

Electrical conduit

Level sensors

SEDIMENTATION TANK

STORAGE TANK

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Post-Storage Treatment

Contaminant Treatment Devices/Options Available

- turbidity - total suspended solids - bacteria > 0.2 microns

• Particle filter (100/50/20/5 micron) • Rapid sand filter • Slow sand filter • Membrane filter

- microbiological contaminants (viruses, bacteria and protozoa)

• Ultraviolet (UV) light • Chlorine • Ozonation • Slow sand filter • Membrane filter

- hydrogen sulfide - organic matter - manganese - iron

• Activated carbon • Ozonation • Particle filter (100/50/20/5 micron) • Slow sand filter • Reverse Osmosis • Ultrafiltration & chemical addition

Particle filter (100/50/20/5 micron)

Ultraviolet (UV) light

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odor taste color

Irrigation system

Toilet

Non-potable water pipeline

Municipal pipeline to

potable fixtures

Make-Up System

Solenoid valve (N/C)

Air gap

N/O

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Backflow Prevention

• Backflow - flowing back of or reversal of the normal direction of flow of water

• Backflow Prevention Device - device that prevents backflow

• Cross-connection – any actual or potential connection between a potable water supply or system and any source of pollution or contamination and includes any by-pass, jumper connection, removable section of pipe, swivel or changeover device and any other temporary connecting arrangement through which backflow may occur.

38 Source: City of Guelph, 2009. Backflow Prevention. http://guelph.ca/living.cfm?smocid=1975

Backflow Prevention

• Reduced Pressure Backflow Preventer (RPBP) – Most Expensive – Requires annual testing – Discharges water

• Double Check Valve Assembly (DCVA) –Annual testing –No water discharge

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Hose bib Irrigation

system

Toilet

Washing machine

Non-potable water pipeline

Municipal pipeline to

potable fixtures

Hot water tank

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What’s Wrong With This Picture?

Make-Up System

Air gap

Rainwater to distribution

Mains water

Rainwater from tank

Solenoid valve

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Item to be inspected Frequency CSA B128.B

Recommendations Additional Recommendations

Roof, gutters, downspouts

6 months Inspect; clean gutters, ensure no blockage.

Trim overhanging branches Sweep debris off roof, as necessary Check in winter for ice build up in gutters/pipes

Filter systems 3 months

Inspect; clean or replace filter as required

Check if rainwater and debris is bypassing filter Assess for frost damage

Storage tanks 12 months* Inspect and clean* as necessary. Check for leaks and repair as necessary.

Excessive settling of tank or moisture in soil around tank may indicate leak *Cleaning the tank annually is not generally recommended. Some biofilm in the tank may help to improve tank-stored rainwater quality.

Pumps and pressure tanks

12 months Inspect and verify operation

Inspect components inside of tank for corrosion or degradation; Inspect electrical splicing Ensure pump is not overheating or cycling on and off too frequently, or when there is no demand 42

Item to be inspected Frequency CSA B128.B

Recommendations Additional Recommendations

Backflow preventers

12 months Following CSA B64.10

Make-Up Systems 6 months Inspect float switches for proper positioning and to ensure they are not tangled Ensure electrical splicing is in tack Simulate float switch action to test solenoid valves

Post-storage treatment

6 months Inspect and verify correct operation.

Overflow system 12 months Discharge to grade – ensure no erosion or entry of bugs/debris/rodents Discharge below grade – check for signs of water damage to hatch or inside access riser, or water discharging at air gap or downspout to pipe transition

Labels and signage 12 months Inspect and replace as necessary.

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Rainwater Harvesting

In Alberta