Using Graywater and Stormwater to Enhance Local Water Supplies An Assessment of Risks, Costs, and Benefits (2016) / Chapter Skim
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9 Graywater and Stormwater in the Context of Integrated Water Supply Planning
9 Graywater and Stormwater in the Context of Integrated Water Supply Planning
Pages 154-166
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From page 154... ...
Decision makers should understand these fac- major steps include defining objectives, identifying opportutors to determine the potential risks, costs, and benefits of nities and constraints, characterizing sites, identifying candiinvestments in graywater and stormwater capture and use date strategies, selecting the system design, implementing the systems at a range of scales at the local level. For small-scale system, and engaging stakeholder involvement throughout systems, home and business owners may want to determine the process.
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From page 155... ...
defined. Stakeholders define the issues and considerations Stakeholder engagement should begin relatively early in that should be addressed in the decision process, and they the decision process so that the relevant issues are appropri- bring a set of values that in an effective process are used ately considered throughout the process.
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From page 156... ...
For example, if reduction of potable water use is health laws (see Tables B-1 and B-2 for major state regulathe primary objective, stormwater capture and use systems tions, although this list is not exhaustive)
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From page 157... ...
Cost savings may be feasible for simple laundry-to-landscape systems based on potable water savings. Cost savings may be feasible based on potable water savings, although capital and maintenance costs of large-scale systems are not well defined.
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From page 158... ...
and recharge conditions exist, although water rights may need • to be acquired. • If water savings are the primary objective, then opportunities • to reduce outdoor irrigation demand should be considered by • Under suitable climatic conditions, multi-residential buildings converting to native landscaping can achieve significant reductions in indoor water use (up to 24% when used for toilet flushing, and more if other nonpotable uses are included)
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From page 159... ...
BOX 9-1 Stakeholder Engagement in Decision Making: Example of Sonoma County The Sonoma County Water Agency in California is undertaking scoping studies to identify stormwater management/groundwater recharge projects that would be located in the Sonoma Valley and Petaluma River watersheds. The process involves (1)
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From page 160... ...
contrast, in the arid Southwest, where precipitation is limited and concentrated in winter months when irrigation demand Identify Candidate Strategies and Components is low, very large storage capacity is needed to significantly reduce potable water demand through stormwater capture. In With a firm understanding of the project objectives these areas, large-scale groundwater recharge is an attractive (Chapter 1)
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From page 161... ...
At a household scale, common objectives of on-site alternative water supply systems include reducing Implementation potable water demand, environmental stewardship, cost sav ings from reduced potable water and wastewater fees, pollu Implementation issues vary in complexity, depending tion prevention (stormwater) , and reliability of water supply on the project's scale.
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From page 162... ...
To minimize the risks of untreated graywater reuse at the household scale, When considering stormwater or graywater capture and residents should comply with best management practices and beneficial use at a household or building scale, it is critical use subsurface (including landscape-covered drip) irrigation to understand the amount of water available relative to the and only irrigate non-food crops.
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From page 163... ...
If sustainability and water pollution ply benefits, water reliability, pollution control, and other control are important objectives, then moderate-sized cisterns project objectives relative to the cost. A full range of ben- can provide substantial water savings (although with longer efits, including social and environmental benefits (see Box payback periods)
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From page 164... ...
. duced potable water and wastewater fees, financial incentives related to stormwater management or extending the capacity Site Characterization -- Water Availability and Quality of existing water and wastewater infrastructure, enhanced water reliability, environmental stewardship, public educa- Stormwater can be captured from rooftops, driveways, tion, pollution prevention, and projecting a "green" image and parking areas, although on-site stormwater capture is that could attract residents or businesses (see Chapter 1 and typically limited to rooftop runoff, because it tends to have Tables 9-2 and 9-3)
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From page 165... ...
For example, a system designed to capture The potential benefits of on-site graywater and/or stormall runoff from a 1-inch storm may be quite different from water capture and use (including potable water savings, a system designed to optimize potable water savings. In the averted wastewater fees, other incentives, pollution prevenarid Southwest, where rainfall is concentrated during peri- tion, energy recovery, environmental stewardship, public ods of low irrigation demand, very large stormwater stor- education, and improved public image)
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From page 166... ...
There is no single best way to use graywater or stormwater to address local water needs, because project drivers Lack of clarity on water rights and legal and regulatory and objectives, legal and regulatory constraints, potential inconsistencies are also impediments to water management applications, site conditions, source water availability, and decision making in some states. More discussion on research project budgets, all vary widely.
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