Drinking water quality statistics

Key figures

Violations and boil notices

• In fiscal year 2021, 6.2 percent of community water systems had one or more health-based violations, affecting 23.9 million people.
• Federal drinking water regulations cover more than 90 contaminants.
• In 2015, 76.9 million people were served by community water systems with at least one reported violation of the Safe Drinking Water Act.
• That year there were 80,834 reported violations, at 18,094 community water systems across the country.
• After Hurricane Helene in September 2024, boil water advisories affected more than 1.8 million people for days to weeks.

Wells, nitrate and waterborne illness

• About 23 percent of more than 2,000 private wells tested had at least one contaminant at a level of potential health concern.
• Nitrate in groundwater used for drinking exceeded the 10 mg/L health benchmark in 9 percent of 4,674 samples.
• 59.5 million people get drinking water from 757 large community water systems that detected nitrate at or above 3 mg/L at least once between 2017 and 2019.
• 60 water systems serving almost 3.9 million people tested at or above the 10 mg/L nitrate limit at least once between 2017 and 2019.
• An estimate based on 2014 data puts waterborne illnesses in the United States at about 7.15 million a year.
• Waterborne diseases are responsible for an estimated 118,000 hospitalizations in the United States each year.
• They are also responsible for an estimated 6,630 deaths a year.

Lead

• The United States is projected to have 9.2 million lead service lines.
• Under the 2024 lead rule, water systems must replace the lead service lines they control in 10 years or less.
• The lead action level moves from 0.015 mg/L to 0.010 mg/L on November 1, 2027.
• A federal law invests $15 billion to identify and replace lead service lines.
• About 500,000 children in the United States have blood lead levels at or above the reference value of 3.5 micrograms per deciliter.
• An estimated 43 percent of school districts, serving 35 million students, tested for lead in school drinking water in 2016 or 2017, and 41 percent, serving 12 million students, had not.
• Among the school districts that tested, an estimated 37 percent found elevated lead.
• The Flint water crisis settlement totals $626.25 million.
• Of the utilities serving the 100 largest U.S. cities, 15 have public lead service line maps.

PFAS

• The federal limit for PFOA and PFOS in drinking water is 4.0 parts per trillion each.
• PFHxS, PFNA and HFPO-DA (GenX) each have a limit of 10 parts per trillion.
• At least 45 percent of the nation's tap water is estimated to have one or more types of PFAS.
• 4,100 to 6,700 public water systems, serving 83 to 105 million people, will need to act to bring PFAS below the standards.
• Once in force, the PFAS rule is expected to reduce exposure for approximately 100 million Americans served by public water systems.
• Compliance with the PFAS rule is estimated to cost approximately $1.5 billion a year.
• $9 billion is available to help communities with drinking water affected by PFAS and other emerging contaminants.

Safe water worldwide

• In 2024, 2.1 billion people still lacked safely managed drinking water, including 106 million who drank directly from untreated surface sources.
• At least 1.7 billion people used a drinking water source contaminated with feces in 2022.
• An estimated 140 million people in at least 70 countries have been drinking water with arsenic above the provisional guideline value of 10 micrograms per liter.
• Unsafe drinking water, sanitation and hygiene could have prevented at least 1.4 million deaths in 2019.
• In 2025, 47 countries reported 451,499 cholera cases and 7,870 deaths.
• In Europe, monitoring found compliance above 99.5 percent for a range of chemical parameters in drinking water.
• 56 percent of the water bodies assessed in 120 countries had good water quality in 2023.