What is Graywater?

Graywater is wastewater generated from domestic activities such as laundry and bathing, which can be recycled on-site for uses such as landscape irrigation and constructed wetlands.

Sources of Graywater

Graywater • Showers/baths • Clothes washer • Sinks (bathroom sinks)

Blackwater (NOT allowed for reuse) • Toilets • Clothes Washer w/ diaper wash water, greasy rags,

other chemicals • Kitchen sinks or dishwashers

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Qualities of Graywater

• High amounts of suspended solids • Nutrients

• fats and oils

• Hair

• Lint

• Soaps, cleaning products

• Bacteria that can rapidly multiply to turn graywater into blackwater

• Basic (alkaline) • Consistent production, does not vary

according to irrigation requirements3

Soaps and water quality

Recommended products: salt & boron free • Liquid laundry detergent

• Oasis, ECOS, Biopac, & more

Things to avoid for happy plants: • Salt (sodium compounds)

• Boron (borate)

• Chlorine bleach (hydrogen peroxide bleach okay)

For graywater systems with filters: avoid bar soap made with fats that can easily clog filters.

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Benefits of Graywater

• Lower potable water use • Saves energy used to produce and distribute potable water; along

with energy saved from the transport and treatment of wastewater • Groundwater recharge • Returns nutrients to the soil • Effective water treatment occurs in the biologically active upper

region of the soil • Reduces demand on wastewater treatment plants and septic

systems • Allows septic systems to work more efficiently • Connects homeowners or customers to how much water they are

using and their product choices • Reliable landscape water source during drought or water shortage

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Cost Benefit Analysis

• Important to consider cost benefit of a proposed graywater system • Complex systems have a high financial cost as well as an

environmental impact • Are the water savings sufficient to justify the proposed system? • More simple graywater systems have a lower cost and impact but

don’t offer high levels of irrigation efficiency • Cost benefit analysis can be shifted in certain situations:

• Failing septic • Emergency water shortage • Large volumes of graywater

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When Not to Use Graywater

• Insufficient space to sustainably infiltrate water • Inaccessible drain pipes, e.g. plumbing encased in

concrete slab • Unsuitable climate, e.g. very wet, irrigation is of little

benefit, freezing may prevent use for part of year • Close proximity to streams or lakes, or water wells, may

cause surface or drinking water contamination • Unsuitable soil

• Extremely permeable, may cause contamination • Impermeable, may cause runoff or ponding

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Potential Graywater Production

10 minute shower • 3.5 gpm shower head = 35 gallons • 2.5 gpm shower head = 25 gallons • 2.0 gpm* shower head = 20 gallons • 1.5 gpm shower head = 15 gallons

*Current CALGreen Plumbing Code

1 load of laundry* • Top loader = 30-50 gallons • Front loader = 15 gallons

*Estimated, refer to manufacturer specifications for actual number

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Potential Vs. Realized Water Savings

Important to recognize that graywater production is not equal to water savings • Water savings typically only occur during the irrigation season

(unless water is treated) • Potential water savings depend on irrigation efficiency of graywater

system being installed compared to pre-existing system • Improper designs won’t save water • Irrigation efficiency of different system types varies significantly • Environmental impact may offset benefits of higher efficiency

• Realized water savings depend on effective water management

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Graywater System Design Considerations. To pump or not to pump?

Gravity fed: Laundry to landscape, branched drain • Simple and robust • Low maintenance • Relatively inexpensive • No supplemental

electricity • Low water use efficiency

(mulch basins) • Best for trees and shrubs

Pumped Systems

• Higher water use efficiency (drip if filtered)

• Ability to send water uphill and long distances

• Increased cost and complexity

• Higher environmental impact offsets water use efficiency

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System Design Overview: Laundry to Landscape

• Doesn’t alter existing plumbing

• No permit required (if guidelines are followed)

• Easy to install • Low cost

11http://www.cleanwatercomponents.com

Mulch Basin

Mulch Basins may be used as an irrigation or disposal field for graywater.

• Prevent runoff • Prevent pooling (exposure)

• Provide surge capacity if sized correctly

• As long as mulch basins are at least 1 ft. deep and sized according to Table 1062.10 sufficient surge capacity is ensured

• Discharge 2 in. under mulch shield for code compliance

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Laundry to Landscape Systems

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Laundry to Landscape Systems

A laundry-to-landscape graywater system captures graywater from the discharge hose of your washing machine, enabling you to reuse the water without altering the existing plumbing in your home Graywater is distributed through an irrigation line with outlets directing water to mulch basins close to specific plants

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Laundry to Landscape Collection Plumbing

• Captures graywater from the discharge hose of your washing machine

• Diversion upstream of drainpipe • No alteration to existing plumbing • Washing machine pump used to distribute graywater • Water is slightly pressurized so the system is less demanding of

strict grade (fall) than a gravity-only system • 3-way diverter valve diverts water either to the landscape or the

septic/sewer • Vacuum breaker or anti-siphon component on the landscape side of

the 3-way valve

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Laundry to Landscape System Overview

Indoor A. Brass 1" 3-way valve B. PVC 1" Male Adapter (S x MPT) C. Barbed 1" Male Adapter (MPT) D. PVC 1" 90 Elbow E. PVC 1" Tee F. PVC 1.5" x 1" Reducing Bushing (SxS) G. PVC 1.5" Female Adapter (FPT x Slip) H. Auto-vent or Air Admittance Valve 1.5”

Outdoor J. Barbed 1" Adapter (BxS) K. Barbed 1" Tee L. Barbed 1" x 1/2" Reducing Tee M. Poly 1/2" Tubing N. 8 - 7" round valve box O. Green Back Valve Barbed 1/2" P. Barbed 1" Coupling

http://www.cleanwatercomponents.com

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Laundry to Landscape Collection Plumbing

3-way diverter valve; Auto vent; 1" pipe (PVC); Swing check Backflow preventer (if water is going uphill)

Photo: Greywater Gardens

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Laundry to Landscape - Step by Step

Laundry to Landscape collection plumbing: Step 1: Connecting the 3-way diverter valve Step 2: Anti-siphon component Step 3: Drilling hole for pipe to exit

Step 4: Plumb to hole Step 5: Plumb to sewer connection Step 6: Strap pipe/diverter valve Step 7: Label pipe and 3-way diverter valve

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Step 1: Connecting the 3-way diverter Valve

1”-brass 3-way diverter valve

Hose clamp

Washer hose (from machine)

1” PVC male adapter

1”PVC barbed male adapter

1”schedule 40 PVC pipe

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Step 1: 3-Way diverter valve Configurations

a. Diverter valve must be above “flood rim” of machine

b. Washer hose must connect to middle port

c. Use teflon tape (on threads) and glue (on slip connections) to make water-tight connections

d. Secure with pipe clamps

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Step 1: Teflon Tape Threaded Fittings

Teflon tape helps prevent leaks • Wrap tape CLOCKWISE several times

over

• Don't “cross-thread” when screwing fitting into 3-way diverter valve

• Tighten with channel locks

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Step 1: Troubleshooting tips for Connecting Washer Hose

Washer hose doesn't fit onto 1” barbed adapter

¾ x 1” threaded bushing

¾” barbed male adapter

• If hose is too large or small use threaded bushing with proper sized barbed adapter

• If hose is slightly too small heat hose with hair dryer or hot water, then forcefully push on

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Step 1: Troubleshooting tips for Connecting Washer Hose

Washer hose connection leaks (rigid hose) • Tighten hose clamps, add 2nd hose clamp • Connect with piece of vinyl tubing

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Step 2: Anti-siphon Component

Used to prevent a potential siphon from forming and draining the machine as it tries to refill • Options

• Autovent, AAV, in-line vent • “breather tube” any vent tall

enough not to emit water • Must be at high point of

system • Must be accessible in

case of leaks and for replacement

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Step 2: Anti-siphon Assembly

Autovent 1 ½” threads

1 ½” FPT (female pipe threads) by slip coupling

Reducing bushing 1 ½” x 1” slip

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Step 2: Placement of Anti-Siphon

• High point • Accessible/visible (not behind a

wall)

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Step 3: Drilling Hole for Pipe to Exit

a. Look for potential issues • electrical lines, insulation type, gas pipes, etc

b. Drill a ¼” pilot hole

c. If no obstructions, drill hole for 1” PVC with

d. 1½” holesaw • drill from outside in, and inside out for a clean looking hole

e. Use proper bit for your wall/floor • wood bit, stucco bit, etc

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Step 4: Plumb to Hole

Cutting PVC pipe • Use PVC cutters or handsaw

• Remember to calculate the length of pipe that will “slip” into the fitting when figuring your measurements

• Use as few fittings as possible to minimize friction

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Step 5: Plumb to Sewer Connection

Gluing PVC Use Gorilla PVC glue if possible (it's much less toxic than regular PVC primer and glue)

1. Clean and dry pipe 2. Apply glue to the inside of the fitting “hub” first 3. Apply glue to the outside of the pipe 4. Push together quickly, inserting all the way, rotate

slightly to spread glue evenly, and hold a second as it will try to push out

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Step 6: Strap Pipe/Diverter Valve

•Use 2-hole straps or plumbers tape •Add wood blocking as necessary •Strap so diverter valve is secure

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Step 7: Label Pipe and 3-way Diverter Valve

• Label pipe: “Caution: Non-potable water, do not drink”

• Label diverter valve showing direction of graywater

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Activity 1: Identifying Parts

Identify and label the images in your Activity.

1. 3-way valve

2. PVC 1-in. male adapter

3. 1-in. barbed male adapter

4. Hose clamp

5. PCV 1-in. x 1.5 in. bushing

6. Auto vent

7. 1-in. PVC tee

8. 1-in. schedule 40 PVC pipe

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Laundry to Landscape Systems

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Laundry to Landscape Distribution

Laundry to landscape distribution Step 1: Piping to irrigation field Step 2: Calculate and dig mulch basins, build mulch shields Step 3: Trench to mulch basins Step 4: Lay tubing Step 5: Test and tune system

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Step 1: Piping to Irrigation Field

● You may have to pipe around decks, patios, etc.

● You may need to bypass hardscape ● Options: go under it, go around

it, remove it, cut a strip of it, cut across the driveway and patch in

● Maintain a downwards slope ● Paint exposed PVC pipe to

protect from UV ● Caulk holes at building exit points

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Step 2: Mulch Basins

Refer to Class 3 and Table 1602.10, for information on sizing the irrigation area

Plan for mature plant size

Type of Soil Minimum sqft of irrigation area per 100 gallons of graywater/

day

Max absorption capacity

(gallon/sqft/ day)

Coarse sand or gravel

20 5.0

Fine Sand 25 4.0

Sandy Loam 40 2.5

Sandy Clay 60 1.7

Clay w/ considerable sand or gravel

90 1.1

Clay w/small amounts of sand or gravel

120 0.8

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Step 2: Mulch Shields

The purpose of a mulch shield is to provide graywater water outlet pipes with protection from soil and plant roots

• Can use small valve boxes or inverted plant containers • Graywater discharge 2 in. under mulch shield for code

compliance

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Step 3: Trench to mulch basins

• Dig a trench, about 4 inches deep, from the PVC pipe to the first mulch basin

• Continue the trench to all the basins, taking the most direct route possible while avoiding sharp turns

• If possible, maintain a slight downward slope or at least a level gradient

• If the system has dips and rises, it will be more difficult to get even distribution of water

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Step 3: Slope

Protect your washing machine's pump: • Flat yard- no more than 50 ft.

• Don't pump more than 2' above the rim of the machine • With friction loss every 50' flat = 1.5' rise

• Downhill slope - no rule on distance • Uphill slope - not recommended! • Use a swing check valve to prevent back flow into the

machine

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Step 4: Lay Tubing

• Roll HDPE tubing out in the trench to mulch basins

• Stake tubing so that it stays in place

• At each irrigation point, cut the tubing and insert a 1 inch x ½ inch barbed tee into the tubing

• Attach short section of ½ inch poly tubing and insert into mulch shield

• Maintain 1 inch open end at some point in the system

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Step 5: Test and Tune System

• Test system for leaks and operation before burying pipes and tubing

• Tune flows in the system • Take photos before burying tubing

to include in O&M manual • Bury tubing • Caulk holes inside and out • Post signs • Post O&M Manual

Adjust angle of tees

Adjust ball valves