As discussed previously, domestic wells tend to be as shallow as possible to keep well construction costs low. They are often installed just deep enough to meet domestic water needs, based on the groundwater levels at the time of well construction. This can make domestic wells vulnerable to future groundwater level declines caused by seasonal drought, climate change, well interference, or aquifer depletion. If groundwater level declines are sufficiently large compared to the available drawdown in a well, the well owner may be faced with a temporary or permanent water shortage. This may require the well owner to make changes to their well, such as lowering the pump or deepening the well. If these solutions do not work, they may need to install a new deeper well or obtain water from an alternate source.
Aquifer depletion is occurring in most of the major aquifers in the world’s arid and semi-arid areas (Famiglietti, 2014). As groundwater levels drop in these aquifers, shallow domestic wells are among the first wells to go dry. Drawing water from new deeper wells may not be possible for domestic well owners because of the increased cost associated with deeper well construction, energy to pump groundwater from greater depth, and treatment of the potentially poorer quality groundwater found at depth.
A drought in California, USA, between 2012 and 2016 was reported to have caused almost 12,000 people to run out of water (Cagle, 2020). The impact of this drought was especially severe in California’s Central Valley where it was estimated that about one in five wells ran dry. Aquifer depletion had already lowered the water table here to 250 m below ground surface in some places (Stokstad, 2020). Domestic wells in the Central Valley are going dry more often than other well types because they tend to be shallower. An analysis of dry wells during the 2012-2016 California drought estimated that 6 percent of agricultural wells and 19 percent of domestic wells went dry during this period (Jasechko and Perrone, 2020). Domestic wells are reported to be shallower than agricultural wells in several agricultural areas around the world (Jasechko and Perrone, 2021), indicating that their vulnerability to groundwater level declines compared to other well types is a global issue.
The problem of dry domestic wells is not restricted to California. In the Western United States, a study evaluated more than two million well records and estimated that about 4 percent of domestic wells went dry between 2013 and 2015 (Perrone and Jasechko, 2017). In Nova Scotia, Canada, a drought in 2016 was reported to have caused more than 1,000 water wells to go dry, 93 percent of which were domestic dug wells (Kennedy et al., 2017). Many municipal governments in Nova Scotia are now providing loans to help well owners install deeper wells.