The SDWA applies to every public water system (PWS) in the United States. There are currently over 151,000 public water systems providing water to almost all Americans at some time in their lives. The Act does not cover private wells (in 2020, 13% of US households were served by private wells). A 2020 study found that children raised in homes with unregulated wells had a 25% increased risk of elevated blood lead than children raised in homes supplied by water utilities regulated by the SDWA.