The main driving force behind the current rapid implementation of ASR technology around the world is water supply economics. ASR systems can usually meet water management needs at less than half the capital cost of other water supply alternatives. When compared to alternatives requiring construction of water treatment plants and surface reservoirs to meet increasing peak demands, potential savings have been known to exceed 90%. A second important driving force has been the increased recognition of this technology as being good for the environment, aquatic and terrestrial ecosystems. By reducing or eliminating the need for construction of dams, and by providing reliable water supplies through diversions of flood flows instead of low flows, ASR systems are usually considered to be environmentally friendly.
Storage zones range in depth from as shallow as about 75 m (200 ft.) to as deep as 900 m (2700 ft.). Groundwater levels in the storage zones range from as much as 10 m (30 ft.) above land surface to more than 300 m (900 ft.) below land surface. Natural water quality in the storage zone ranges from fresh, suitable for drinking without treatment, to brackish,including total dissolved solids concentrations up to about 5000 mg/l. Most sites have one or more natural water quality constituents that are unsuitable for direct potable use except following treatment. Such constituents may include iron, manganese, fluoride, hydrogen sulfide, sulfate, chloride, radium (224/226 /228), gross alpha radioactivity, and other elements which are typically displaced by the stored water as the bubble is formed underground. At one site, not currently in operation, ASR was shown to be feasible and highly cost-effective storing drinking water in an aquifer containing seawater. For most of these sites, it is first necessary to properly develop the storage zone around the well, after which it is possible to recover the same volume as that stored. At a few, more challenging sites water quality, hydraulic or geochemical constraints may limit recovery to somewhat less than the volume stored.
available supplies, treated wastewater is reclaimed and piped to golf courses, parks, gardens and other areas requiring irrigation to reduce the demand for potable water. When the rains begin and irrigation demand ceases, reclaimed water is stored in ASR wells in deep brackish aquifers, from which it is recovered when needed to meet irrigation demands during dry periods. Reclaimed water ASR is therefore beginning to be a booming application of the ASR technology.