Congress of the United States


Date of this Version



Published by Congressional Research Service, 7-5700,, R40477


In the United States, desalination is increasingly investigated as an option for meeting municipal water demands, particularly for coastal communities that can desalinate seawater or estuarine water, interior communities above brackish groundwater aquifers, and communities with contaminated water supplies. Adoption of desalination, however, remains constrained by financial, environmental, regulatory, and other factors. At issue is what role Congress establishes for the federal government in desalination research and development, and in construction and operational costs of desalination demonstration projects and full-scale facilities.

Desalination processes generally treat seawater or brackish water to produce a stream of freshwater, and a separate, saltier stream of water that has to be disposed (often called waste concentrate). Desalination’s attractions are that it can create a new source of freshwater from otherwise unusable waters, and that this source may be more dependable than freshwater sources that rely on annual or multi-year precipitation, runoff, and recharge rates. Many states (most notably Florida, California, and Texas) and cities are actively researching and investigating the feasibility of large-scale desalination plants for municipal water supplies.

Desalination and its different applications, however, come with their own sets of risks and concerns. Although the costs of desalination dropped steadily in recent decades, making it more competitive with other water supply augmentation options, the declining trend may not continue if energy costs rise. Electricity expenses vary from one-third to one-half of the operating cost of desalination facilities. Reducing the energy requirements of desalination would decrease its cost uncertainties. Substantial uncertainty also remains about the technology’s environmental impacts, in particular management of the saline waste concentrate and the effect of intake facilities on aquatic organisms. Moreover, there are few federal health and environmental guidelines, regulations, and policies specific to desalination as a municipal water supply source. Social acceptance and regulatory processes also affect desalination’s adoption and perceived risks. Research and public education may help to resolve some uncertainties, develop methods to mitigate impacts, reduce the costs of desalination, and improve public understanding of the risks.

To date, the federal government has been involved primarily in desalination research and development (including military applications), some demonstration projects, and select full-scale facilities. For the most part, local governments, sometimes with state-level involvement, have been responsible for planning, testing, building, and operating desalination facilities, similar to their responsibility for freshwater treatment for municipal drinking water supply. Bills in the 111th Congress (e.g., H.R. 88, H.R. 469, S. 1462, S. 1731, S. 1733, and P.L. 111-11) represent a range of federal authorizations for desalination research, demonstration and full-scale facilities, and planning and financing. H.R. 1145 would formally establish a federal interagency committee to coordinate federal water research, including desalination research.