Private wells
Private wells are not regulated by EPA, and public water system records do not apply to them. The well owner is responsible for testing and treatment.
NH DES recommends testing bacteria and nitrate/nitrite every year, and the rest of its Standard Analysis (including arsenic, uranium, lead and copper) every 3 to 5 years. It also recommends testing for radon and PFAS. Test again after flooding or a change in taste or smell.
Use a lab accredited under the NH Environmental Laboratory Accreditation Program (NHELAP).