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National Drinking Water Database

National Drinking Water Database - Chemical Contaminants


Status: Unregulated - EPA has not established a maximum legal limit in tapwater for this contaminant.

Perchlorate is a synthetic oxygen additive in solid fuel propellant for rockets, missiles, and fireworks, and is primarily used by the military and the space industry; it may occur naturally in certain imported agricultural fertilizers. [read more]

Found above
health guidelines
Found above
legal limit
Water utilities
People Served

Perchlorate Exposure by State

Water utilities in 7 states have reported detecting Perchlorate in treated tap water since 2004, according to EWG's analysis of water quality data supplied by state water agencies.

StateWater Suppliers with Perchlorate contaminationWater suppliers reporting Perchlorate above health-based limits
New York25835,43211448,896
New Hampshire221,82500
New Mexico18,17700

The Most Polluted Communities

279 water utilities reported detecting Perchlorate in tap water since 2004, according to EWG's analysis of water quality data supplied by state water agencies

Ranked by highest average Perchlorate level

RankSystem Population Served Positive test results of total reported tests Average Level
1LA Puente Valley Cwd
La Puente, CA
7,500271 of 28320.96 ppb
(0 to 68 ppb)
2San Gabriel Valley Water Co.-El Monte
El Monte, CA
153,657232 of 23514.13 ppb
(0 to 50 ppb)
3Yermo Water Co
Victorville, CA
1,1001 of 511.14 ppb
(0 to 55.7 ppb)
4Lincoln Avenue Water Co.
Altadena, CA
16,000248 of 2528.96 ppb
(0 to 18.4 ppb)
5City of Lindsay
Lindsay, CA
11,1857 of 98.11 ppb
(0 to 13 ppb)
6EL Rio Estates
Anderson, CA
4501 of 37.33 ppb
(0 to 22 ppb)
7LA Quinta Ridge Mobile Estates
Indio, CA
3503 of 36.63 ppb
(6.4 to 7 ppb)
8Lamont Public Utility Dist
Lamont, CA
14,0003 of 66.08 ppb
(0 to 20 ppb)
9Tokay Park Water Co
Sacramento, CA
5255 of 65.89 ppb
(0 to 10 ppb)
10City of Chino
Chino, CA
52,13012 of 145.76 ppb
(0 to 13 ppb)

Health Based Limits for Perchlorate

Health-Based Screening LevelA benchmark concentration of contaminants in water that may be of potential concern for human health, if exceeded. For noncarcinogens, the HBSL represents the contaminant concentration in drinking water that is not expected to cause any adverse effects over a lifetime of exposure. For carcinogens, the HBSL range represents the contaminant concentration in drinking water that corresponds to an excess estimated lifetime cancer risk of 1 chance in 1 million to 1 chance in 10 thousand. Source: U.S. Geological Survey.5 ppb
California Public Health GoalsDefined by the State of California Office of Environmental Health Hazard Assessment (OEHHA) as the level of contaminant that is allowed in drinking water. For acutely toxic substances, levels are set at which scientific evidence indicates that no known or anticipated adverse effects on health will occur, plus an adequate margin-of safety. PHGs for carcinogens or other substances which can cause chronic disease shall be based solely on health effects without regard to cost impacts and shall be set at levels which OEHHA has determined do not pose any significant risk to health.6 ppb

Testing Summary for Perchlorate

Are tests routinely required for Perchlorate by federal law?No
Water suppliers reporting tests for Perchlorate (2004-2009):2,604 of 47,576
Average testing rate for water supplier reporting tests (2004-2009):1.2 per year