The Water Map

Disinfection byproducts

Perchlorate in U.S. tap water

233 public water systems across 8 U.S. states report Perchlorate in their annual Consumer Confidence Report. None currently sit at or above the federal limit.

233
systems measuring
0
over the limit
8
states represented

What it is

A chemical used in rocket fuel and fireworks that can also form during disinfection.

Why it's regulated

Can interfere with thyroid hormone production; has no national enforceable limit but is regulated in some states.

Federal limit1 ug/L· Public health goal

Within the federal limit (47)

Water systemMeasured
Antelope Valley East Kern Water Agency — Palmdale, Ca, CA
2020 annual report
Not detected ug/L
Antelope Valley East Kern Water Agency — Palmdale, Ca, CA
2021 annual report
Not detected ug/L
Antelope Valley East Kern Water Agency — Palmdale, Ca, CA
2022 annual report
Not detected ug/L
Boron Csd — Boron, Ca, CA
2022 annual report
Not detected ug/L
Calif State Polytechnical Univ - Pomona — Pomona, Ca, CA
2020 annual report
Not detected ug/L
Carpinteria Valley Water District — Carpinteria, Ca, CA
2023 annual report
Not detected ug/L
Cci - Tehachapi — Tehachapi, Ca, CA
2023 annual report
Not detected mg/L
City of Lincoln — Lincoln, Ca, CA
2023 annual report
0 ug/L
City of Orange Cove — Orange Cove, Ca, CA
2023 annual report
Not detected ug/L
Covina Irrigating Co. — West Covina, Ca, CA
2020 annual report
Not detected ug/L
Covina Irrigating Co. — West Covina, Ca, CA
2021 annual report
Not detected ug/L
Kinneloa Irrigation Dist. — Pasadena, Ca, CA
2022 annual report
Not detected ug/L
La Canada Irrigation Dist. — La Canada, Ca, CA
2022 annual report
Not detected ug/L
La Canada Irrigation Dist. — La Canada, Ca, CA
2023 annual report
Not detected ug/L
La Canada Irrigation Dist. — La Canada, Ca, CA
2020 annual report
Not detected ug/L
Llano Del Rio Water Company — Llano, Ca, CA
2022 annual report
Not detected
Llano Del Rio Water Company — Llano, Ca, CA
2023 annual report
Not detected
Llano Del Rio Water Company — Llano, Ca, CA
2020 annual report
Not detected
Llano Del Rio Water Company — Llano, Ca, CA
2021 annual report
Not detected
Llano Mutual Water Company — Llano, Ca, CA
2023 annual report
Not detected
Llano Mutual Water Company — Llano, Ca, CA
2020 annual report
Not detected
Llano Mutual Water Company — Llano, Ca, CA
2022 annual report
Not detected
Llano Mutual Water Company — Llano, Ca, CA
2021 annual report
Not detected
Lockeford Community Serv. Dist. — Lockeford, Ca, CA
2023 annual report
Not detected ug/L
Madera Co Md10a-madera Ranchos — Madera, Ca, CA
2023 annual report
Not detected ug/L
Malaga County Water District — Fresno, Ca, CA
2021 annual report
Not detected
Maywood Mutual Water Co. #3 — Maywood, Ca, CA
2022 annual report
Not detected ug/L
Maywood Mutual Water Co. #3 — Maywood, Ca, CA
2021 annual report
Not detected ug/L
Mojave Pud — Mojave, Ca, CA
2023 annual report
Not detected ug/L
North Gualala Water Company — Gualala, Ca, CA
2023 annual report
Not detected ug/L
North Tahoe Pud - Main — Tahoe Vista, Ca, CA
2021 annual report
Not detected ug/L
Nuevo Water Company — Nuevo, Ca, CA
2022 annual report
Not detected ug/L
Rialto, CA
2024 annual report
Not detected ug/L
Sacramento Suburban Water District — Sacramento, Ca, CA
2023 annual report
Not detected ug/L
San Gabriel Valley Water Co-montebello 1 — El Monte, Ca, CA
2023 annual report
Not detected ug/L
San Gabriel Valley Water Co.-el Monte — El Monte, Ca, CA
2023 annual report
Not detected ug/L
Sheep Creek Water Company — Phelan, Ca, CA
2023 annual report
0 ug/L
South Tahoe Pud - Main — South Lake Tahoe, Ca, CA
2023 annual report
Not detected ug/L
Thermalito Water & Sewer Dist — Oroville, Ca, CA
2023 annual report
Not detected ug/L
Three Valleys MWD — Claremont, Ca, CA
2023 annual report
Not detected ug/L
Thunderbird Cwd — Apple Valley, Ca, CA
2023 annual report
0 ug/L
White Fence Farms Mwc No. 1 — Palmdale, Ca, CA
2021 annual report
Not detected
White Fence Farms Mwc No. 1 — Palmdale, Ca, CA
2020 annual report
Not detected ug/L
White Fence Farms Mwc No.3 — Lancaster, Ca, CA
2020 annual report
Not detected ug/L
White Fence Farms Mwc No.3 — Lancaster, Ca, CA
2021 annual report
Not detected ug/L
White Fence Farms Mwc No.3 — Lancaster, Ca, CA
2022 annual report
Not detected ug/L
Yosemite Spring Park Util Co — Coarsegold, Ca, CA
2023 annual report
Not detected ug/L

Frequently asked

+What is Perchlorate?

A chemical used in rocket fuel and fireworks that can also form during disinfection. Can interfere with thyroid hormone production; has no national enforceable limit but is regulated in some states.

+What is the federal limit for Perchlorate in drinking water?

The federal Public health goal for Perchlorate is 1 ug/L. The EPA enforces this against the regulated reporting statistic (typically a running annual average or 90th percentile), not a single-sample spike.

+How many U.S. water systems have Perchlorate over the federal limit?

Zero of the 233 public water systems in The Water Map dataset currently report Perchlorate at or above its federal limit.

+How can I check if Perchlorate is in my city's tap water?

Search your city on The Water Map (https://www.thewatermap.com/) or browse the list on this page. Every U.S. public water utility is required to publish an annual Consumer Confidence Report that lists every contaminant it measured, including Perchlorate.

See Perchlorate on the map

Color-coded by status across the whole country.

Open the map →