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EWG's Tap Water Database — 2021 UPDATE

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Diquat

Great Oaks Water Company Inc.

Diquat is a herbicide used on potato crops and aquatic weeds.

MORE ABOUT THIS CONTAMINANT

 

56

Samples

0

Samples exceeding legal limit (MCL)

0

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
2014ND70ND
2015N/A00N/A
2016ND260ND
2017ND80ND
2018N/A00N/A
2019ND150ND

ppb = parts per billion

State and national drinking water standards and health guidelines

EWG Health Guideline 6 ppb

The EWG Health Guideline of 6 ppb for diquat 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 cataracts.

EPA Maximum Contaminant
Level (MCL) 20 ppb

The legal limit for diquat, established in 1992, was based on a toxicity study in laboratory animals conducted in the 1980s.

ppb = parts per billion

All test results

Date Lab ID Result
2014-03-279590-013-1030ND
2014-05-159590-022-1450ND
2014-05-159590-021-1525ND
2014-05-159590-013-1115ND
2014-08-259590-022-1505ND
2014-08-259590-021-1545ND
2014-08-279590-013-1230ND
2016-05-249590-013-0915ND
2016-05-249590-001-1055ND
2016-05-249590-008-1005ND
2016-05-249590-002-1140ND
2016-05-259590-025-1415ND
2016-05-259590-004-0850ND
2016-05-259590-019-1300ND
2016-05-259590-009-0945ND
2016-05-259590-018-1140ND
2016-05-259590-011-1015ND
2016-05-259590-015-1055ND
2016-05-269590-023-1350ND
2016-08-229590-004-1230ND
2016-08-229590-009-1410ND
2016-08-229590-011-1325ND
2016-08-249590-023-1405ND
2016-08-249590-018-1315ND
2016-08-249590-015-1450ND
2016-08-249590-013-1230ND
2016-08-259590-008-1255ND
2016-08-259590-001-1205ND
2016-08-259590-002-1435ND
2016-08-259590-019-1350ND
2016-09-069590-007-1400ND
2016-09-289590-025-1400ND
2016-11-029590-025-1115ND
2017-03-089590-025-0930ND
2017-04-139590-022-1050ND
2017-04-139590-021-1120ND
2017-04-139590-006-1000ND
2017-06-019590-010-1030ND
2017-08-309590-021-1510ND
2017-08-319590-022-1515ND
2017-08-319590-025-1440ND
2019-05-219590-006-1100ND
2019-05-219590-007-1000ND
2019-05-219590-002-0915ND
2019-05-219590-008-1415ND
2019-05-219590-001-1500ND
2019-05-229590-013-1510ND
2019-05-229590-010-1045ND
2019-05-229590-015-1310ND
2019-05-229590-009-1350ND
2019-05-239590-023-1530ND
2019-05-239590-025-1445ND
2019-05-239590-019-1015ND
2019-05-239590-004-1110ND
2019-05-239590-011-0915ND
2019-05-239590-018-1330ND