EWG's Tap Water Database — 2021 UPDATE



Del Oro Water Company - Country Estates 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
20143.30 ppb113.30 ppb
20154.30 ppb114.30 ppb
20189.09 ppb334.96 ppb - 16.5 ppb
20195.68 ppb335.10 ppb - 6.61 ppb

ppb = parts per billion

State and national drinking water standards and health guidelines

EWG Health Guideline 0.004 ppb

The EWG 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.

EPA Maximum Contaminant
Level (MCL) 10 ppb

The legal limit for arsenic, established in 2001, was based on costs for arsenic removal, as calculated at the time that the standard was set. This limit does not fully protect against the risk of cancer due to arsenic exposure.

ppb = parts per billion

All test results

Date Lab ID Result
2014-05-067473-001-11003.30 ppb
2015-07-077473-001-12004.30 ppb
2018-07-037473-001-102016.5 ppb
2018-08-077473-001-11154.96 ppb
2018-11-067473-001-12355.87 ppb
2019-02-057473-001-11455.32 ppb
2019-08-067473-001-13006.61 ppb
2019-11-057473-001-11405.10 ppb