Drinking water samples failing standards
Share of tested public water supply samples that did not meet the standards, %
About this metric
The chart shows what share of drinking-water samples from the public water supply did not meet the standards in laboratory tests, separately for chemical and microbiological tests. A failing sample is one that missed a limit. The figure does not say how many people were affected or what effect it had on health.
Microbiological tests failed in 18.5% of samples in 2010. The share fell to 6.7% in 2016, rose again to 17.9% in 2018 and was 14.0% in 2024. Chemical tests failed in 10.0% of samples in 2010 and in 3.7% in 2024.
The number of samples tested changed a lot. Microbiological samples tested fell from 158,442 in 2016 to 78,417 in 2017, 49,443 in 2018 and 29,111 in 2024; chemical ones from 148,744 in 2016 to 27,263 in 2024. After 2016 the shares rest on far fewer samples. The source does not say why.