EWG's Tap Water Database — 2021 UPDATE



Walnut Hill Water

Chloromethane is an industrial solvent, aerosol propellant and a refrigerant. It also forms as a byproduct of water disinfection. The EPA classifies chloromethane as possibly carcinogenic to humans.





Samples exceeding legal limit (MCL)


Samples exceeding
health guidelines

Testing results - average by year

YearAverage resultSamples takenDetectionsRange of results
20141.18 ppb111.18 ppb
20151.28 ppb221.17 ppb - 1.39 ppb
20160.365 ppb21ND - 0.730 ppb
20170.784 ppb53ND - 1.77 ppb
20180.555 ppb64ND - 1.000 ppb
20190.458 ppb54ND - 0.640 ppb

ppb = parts per billion

State and national drinking water standards and health guidelines

EWG Health Guideline 2.69 ppb

The EWG Health Guideline of 2.69 ppb for chloromethane was defined by the Environmental Protection Agency as a benchmark for testing under the Unregulated Contaminant Monitoring Rule program. This health guideline protects against cancer.

ppb = parts per billion

All test results

Date Lab ID Result