Maine Septic & Well Water Rules

Maine CDC's Subsurface Wastewater Unit administers the state's septic rules and licenses the professionals who design systems.

This is a short state page. It covers only the facts we've verified from official sources so far.

Official lookups

Maine's Subsurface Wastewater Disposal Rules are 10-144 CMR Chapter 241 (current rule effective September 23, 2023).
Systems are designed by Licensed Site Evaluators, built by installers, and checked by inspectors. Your Local Plumbing Inspector (LPI) is the local contact.

Under 30-A MRS § 4216, properties with a septic system in the shoreland zone must have the system inspected by a Department-certified inspector when ownership is transferred.

Private wells in Maine are not regulated. Owners are responsible for testing and treatment.
Maine CDC recommends testing every year for coliform bacteria, E. coli, nitrates and nitrites, and every 3-5 years for arsenic, chloride, copper, fluoride, hardness, iron, lead, magnesium, manganese, pH, radon, sodium and uranium.
Also test when buying a home, when expecting a baby, after well work or treatment changes, or if the water's smell, taste or color changes. Maine CDC offers free advice and has a test kit option for low-income households.

Is a septic inspection required to sell a house in Maine?

For properties with a septic system in the shoreland zone, yes. 30-A MRS § 4216 requires an inspection by a certified inspector at transfer.

How often should I test my well in Maine?

Maine CDC recommends bacteria and nitrate/nitrite every year and a broader panel (including arsenic, radon and uranium) every 3-5 years.

Last checked: October 21, 2026