EWG's Tap Water Database



Magna Water District

Arsenic is a potent carcinogen and common contaminant in drinking water. Arsenic causes thousands of cases of cancer each year in the U.S. Click here to read more about arsenic.





Samples exceeding legal limit (MCL)


Samples exceeding
health guidelines

Testing results - average by year

YearAverage resultSamples takenDetectionsRange of results
201314.7 ppb2214.7 ppb
20154.85 ppb29291.80 ppb - 11.0 ppb

ppb = parts per billion.

State and national drinking water standards and health guidelines

Health Guideline 0.004 ppb

The health guideline of 0.004 ppb for arsenic was defined by the California Office of Environmental Health Hazard Assessment as a public health goal, the level of a drinking water contaminant that does not pose a significant health risk. This health guideline protects against cancer.

ppb = parts per billion.

EPA Maximum Contaminant
Level (MCL) 10 ppb

The enforceable federal standard that defines the highest level of a contaminant allowed in drinking water.

ppb = parts per billion.

EPA Maximum Contaminant
Level Goal (MCLG)0 ppb

A non-enforceable federal health guideline. For cancer-causing chemicals, these health goals are typically set to zero.

ppb = parts per billion.

All test results

Date Result
2013-02-0814.7 ppb
2013-02-0814.7 ppb
2015-01-072.10 ppb
2015-01-076.30 ppb
2015-02-032.50 ppb
2015-02-037.30 ppb
2015-03-025.10 ppb
2015-03-021.90 ppb
2015-04-075.80 ppb
2015-04-079.70 ppb
2015-04-0711.0 ppb
2015-04-075.80 ppb
2015-05-1911.0 ppb
2015-05-196.40 ppb
2015-05-196.40 ppb
2015-05-192.50 ppb
2015-05-192.50 ppb
2015-06-017.10 ppb
2015-06-012.30 ppb
2015-06-017.10 ppb
2015-06-012.30 ppb
2015-08-064.20 ppb
2015-08-064.00 ppb
2015-09-035.30 ppb
2015-09-032.00 ppb
2015-10-083.60 ppb
2015-10-082.30 ppb
2015-11-121.80 ppb
2015-11-124.60 ppb
2015-12-032.10 ppb
2015-12-035.60 ppb