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Future of Graywater

Objectives

1. Constructed wetland systems

2. Large scale commercial systems

3. Emerging graywater technologies

4. Case studies

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Constructed Wetland Systems

Constructed Wetlands can…

• Be a treatment and disposal system appropriate for urban settings with limited space and high graywater flow

• Mulch, soil, and roots in mulch basins are almost always more ecological and cost effective than a constructed wetland!

• Wetlands are appropriate where there is abundant graywater and little irrigation demand

• Be used as a surge protector

• Encourage evapotranspiration of water

• Remove nutrients

• Filter particles

• Be harder to obtain permits for than other systems

• Be higher maintenance than other graywater systems 3

Constructed Wetland Systems

Pros

• Create beauty / water feature

• Reduce water flow, can take up excess graywater

• Filters graywater for use in drip irrigation

Cons

• Less water available for irrigation

• Needs extra space

• Potential clogging in system

• Increase in materials and cost

• Uses gravel / rock (mined from rivers)

• Doesn't remove chemicals or salt

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Graywater enters wetland in open area with large rocks

to prevent clogging

Graywater outlet needs large rocks to prevent clogging, flows out the

overflow in the tub

• Water tight container or pond liner: graywater flows through substrate (usually gravel or rock) and out the other side

• Graywater is subsurface by at least 2 inches where graywater enters and in the planter used for overflow

Source: Dam Nation

Constructed Wetland - Above Ground

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Source: Virgina Cooperative Extension

• Most of wetland area filled with rock and plant roots

• Only ¼ of the volume is available for water

• To size wetland multiply the gallons of graywater produced by 4 (or divide by 0.25)

¾ of volume filled with rock and roots

¼ of volume air spaces withroom for graywater

Graywater in

Graywaterout

Constructed Wetland - Sizing to Accommodate Peak Flow

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Large-scale, Commercial Systems

Examples

• Hyphae Design Laboratory

• ReWater

• Living Machine Systems

• SFPUC, San Francisco

• Wahaso Water Harvesting Solutions

• West Texas A&M Residence Hall

• Aquacell Water Recycling Solutions

• 181 Freemont, San Francisco

• Graywater systems with a high degree of treatment to facilitate storage and non-potable indoor use

• Engineering companies that can look at all aspects of water in a facility

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Large-scale, Commercial SystemsExample: UCSD Keeling Apartments

• University of California, San Diego

• 600 beds

• Approximately 30,000 / day

• Water used living roof and landscape irrigation

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Large-scale, Commercial SystemsExample: ReWater NRDC

• Natural Resources Defence Council office in Santa Monica, CA

• 2003: Installed an engineered system, filtered greywater and rainwater for toilet flushing and irrigation

• NRDC removed system due to high operational costs

• 2013 installed a ReWater system for irrigation of pots and planters around the office building 9

Emerging Graywater Technologies

• Systems are relatively new

• Typically unproven in US

• Most come from Australia

• Check with your jurisdiction if permitted

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Residential Treatment Systems

• Various systems that provide onsite water treatment so that water can be used for non-potable applications such as toilet flushing and above ground irrigation

• CPC 1601.7.2 requires that water be treated to the MSF 350 standard for non-potable applications

• To date no systems have met this standard

• Examples:

• Nexus eWater

• Aqua2use

• Brac Systems

• Nubian

• Pontos Aquacycle11

Residential Treatment SystemsExample: Nexus eWater

• Recycles gray water to a level safe to use on lawns and toilets

• System uses hybrid floatation cleaning method (no chemicals or biological treatment)

• Filtered water stored in tank for later use

• Capable of 200 gallons per day

• Gray water is used as a heat source for heating potable water, reducing the energy required

• Approximate cost of parts $4,000 or $6,500 including heating module

• Currently seeking NSF 350 certification12

Sink Units

AQUS• chlorine tablets, pump,

filter

Sink Positive• toilet tank fills from faucet

www.aqussystem.com www.sinkpositive.com

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Case Study: Barndance Laundry-to-Landscape, In -Progress

Excavation for mulch basinsfor infiltrating graywater

Outlets in “mulch shields” constructed from valve

boxes

1” HDPE pipe used for distribution plumbing

Case Study: Barndance Laundry-to-Landscape, Complete

Mulch Basins for infiltrating graywater,

multi-function as pathways

Graywater outlet in mulch shieldRainwater outlet

from downspouts

Fruit tree irrigated with graywater

Total project cost $1,500 15

Case Study: BurndaleBranched Drain, Overview

• First Permitted graywater system in Sonoma Valley

• Whole-house system branched drain from 3-bedroom single family home

• Two separate 3-way valves with actuators

• 24 graywater outlets

• Total estimated graywater discharge: 40 gpd/occupant x 4 occupants = 160 gallons per day (gpd) or 1,120 gallons per week (gpw)

• Soil type: Clay w/ low amounts of sand/gravel

• Maximum absorption capacity: 0.8 gallons per square foot per day

• Minimum Irrigation Area: 200 square feet16

Case Study: BurndaleBranched Drain, Plot Plan

Case Study: BurndaleBranched Drain, In Progress

Excavation for mulch basinsfor infiltrating graywater

Outlets in “mulch shields” constructed from lengths of 6” perforated drainpipe

Flow splitters (double ells)divide flow, extend to outlets

1.5” ABS pipe used for distribution plumbing

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Case Study: BurndaleBranched Drain, After Installation

Mulch Basinsfor infiltrating graywater

Graywater outlet in mulch shield

Fruit trees irrigated with graywater

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Case Study: BurndaleBranched Drain, Complete

Case Study: Glen EllenPumped Filtered Drip, Overview

• Diverts graywater produced from 3-bedroom single family home, coupled with rainwater harvested on the property and potable water

• 16 hydro zones over approximately 7,550 square feet of landscaped area

• Graywater is collected in a pumping basin, self-cleaning filter assembly to sub-surface drip zones

• Rainwater collected in four 2,500 gallon tanks plumbed together in-line

• Rainwater used for above-ground spray irrigation zones

• IrriGRAY smart control system

• Laundry diverted through independent L2L system21

Case Study: Glen EllenPumped Filtered Drip, Hydrozone Plan

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Case Study: Glen EllenPumped Filtered Drip, Equipment Plan

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Case Study: Glen EllenPumped Filtered Drip, Manifold Detail

Case Study: Glen EllenPumped Filtered Drip, Drip Zone Detail

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References and Resources

Laura Allen | greywateraction.orgPaul James | graywater-gardening.com | besthomewatersavers.com• IrriGray System

Robert Kourik | robertkourik.com• Drip Irrigation for Every Landscape and All Climates

• Roots Demystified

Art Ludwig | oasisdesign.net • Create an Oasis with Greywater

• Builder’s Greywater Guide

• Water Storage

• Principles of Ecological Design

Brad Lancaster | harvestingrainwater.com• Rainwater harvesting for drylands and beyond

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