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California has a long history of investing in urban water use efficiency and conservation. Faced with drought, rising water costs, and climate change, in 2018 the state passed legislation for “Making Conservation a Way of Life” (AB 1668-SB 606), requiring urban retail water suppliers, who overall serve 36 million residents, to meet water budget targets based on efficient water use standards set by the Legislature (approved by the Governor) and the State Water Resources Control Board (State Water Board).
In 2022, SB 1157 (Hertzberg) updated the indoor residential water use standard and directed the California Department of Water Resources (DWR), in coordination with the State Water Board, to evaluate indoor residential water use and quantify impacts of the lower indoor residential water use standard on water supply, wastewater, and recycled water systems.
Starting in May 2025, a multi-university team began working with DWR to quantify benefits and impacts the 2030 indoor residential water use standard and inform its long-term implementation.
Led by the California Institute for Water Resources (CIWR) within UC Agriculture and Natural Resources, the project team includes experts from CIWR, UCLA (Luskin Center for Innovation and Department of Civil and Environmental Engineering), UC Merced, the Office of Water Programs at Sacramento State, and UC Riverside.
The team will focus on forecasting future water demand and efficiency trends in California cities, evaluating links between urban water supply and wastewater systems, understanding potential impacts to recycled water production, and assessing impacts on affordability for systems across the state.
The team will provide findings to DWR by January 2028. The project is part of multiple studies by DWR to evaluate current and future indoor water use in urban retail water suppliers, which are defined as systems that serve over 3,000 connections or provide at least 3,000 acre-feet of water to retail customers. The studies will incorporate expertise of Technical Advisory Panels and Working Groups comprised of industry, government, and nonprofit experts.
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