Perchlorate in Drinking Water
EPA limits, health effects, and what to do if your water is affected.
🩨 Health Effects
Perchlorate interferes with the thyroid gland's ability to produce hormones needed for normal metabolism. Children, fetuses, and people with thyroid disorders are most vulnerable. Long-term exposure can cause hypothyroidism and may impair fetal neurodevelopment.
📍 Sources in Water
Perchlorate contamination in drinking water comes from rocket fuel and explosives manufacturing, military installations, fireworks, and airbag inflators. It also occurs naturally in some arid western soils. Contamination is most prevalent in California, Texas, Nevada, and near defense manufacturing sites.
✅ What To Do
In 2023, the EPA finalized the first national drinking water standard for perchlorate, setting an MCL of 56 parts per trillion (0.000056 mg/L). Ion exchange and reverse osmosis are effective treatment methods. Water systems have until 2028 to comply with the new standard.
Check your tap water for Perchlorate
Search your ZIP code to see if your water system has had Perchlorate violations, plus lead testing results and an overall safety grade.
Search your ZIP code →Data from the EPA's Safe Drinking Water Information System (SDWIS). MCLs reflect minimum federal standards; some contaminants may pose health risks below these thresholds.