Question 1

Which county in New Hampshire has the best water quality?

Accepted Answer

Sullivan County has the highest water quality score in New Hampshire at 100.0/100 (Grade: C), based on EPA SDWIS data.

Question 2

Which county in New Hampshire has the most water violations?

Accepted Answer

Carroll County has among the lowest water quality scores in New Hampshire at 97.9/100. See the individual county page for detailed violation history.

Question 3

Is the tap water safe to drink in New Hampshire?

Accepted Answer

New Hampshire has an average water quality score of 99.5/100 based on EPA Safe Drinking Water Act compliance data. Individual county scores vary — check your specific county's page for detailed information.

Question 4

What contaminants are found in New Hampshire water supplies?

Accepted Answer

Drinking water quality varies by county and water system. The EPA Safe Drinking Water Information System (SDWIS) tracks violations for contaminants like lead, nitrates, bacteria, and disinfection byproducts. See individual county pages for specific contaminant and violation history.

County	Water Score	Grade	Violations	Violation Rate
Sullivan County	100.0	C	2	8.2%
Cheshire County	99.9	C	7	14.5%
Coos County	99.9	D	4	16.8%
Hillsborough County	99.9	D	89	29.6%
Strafford County	99.8	F	40	43.5%
Grafton County	99.6	F	51	78.7%
Rockingham County	99.6	F	164	82.5%
Merrimack County	99.4	F	112	126.6%
Belknap County	99.0	F	91	222.5%
Carroll County	97.9	F	177	465.2%

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