FAQs - Private Wells

What are private water supplies, who regulates them, recommendations for testing, and more.

What is a private water supply [private well]?

A private water supply provides water for human consumption and consists of a system that has less than fifteen service connections and either (1) serves less than twenty-five individuals or (2) serves an average of twenty-five or more individuals daily for less than sixty days of the year. The term "private well" is typically used for a well that provides drinking water for a single family residence.

Who regulates private wells?

Under Massachusetts General Law (MGL Ch.111 s.122), local Boards of Health (BOHs) have primary jurisdiction over the regulation of private wells. The local BOH is empowered to adopt a Private Well Regulation that establishes criteria for private well siting, construction, water quality and quantity.

Who can drill a well?

As required by 310 CMR 46.00, only Massachusetts Registered Well Drillers are permitted to install wells in the Commonwealth. This includes all well construction types, for both potable and non-potable purposes.

Additional Resources

Where can I find information about my well (well completion report(s))?

Upon installation of a well, a well driller is required to submit copies of the Well Completion Report to the local BOH and the MassDEP Well Driller Program. By contacting either office, you should be able to get a copy of your Well Completion Report, which contains well construction details and geologic descriptions.

When should my well water be tested?

MassDEP recommends that before purchase, prospective homebuyers test the water in a home with a private well. Once you've purchased the home, the interval between water quality tests can generally be in terms of years if the well is properly constructed and located in a safe area. However, the following conditions would prompt more frequent testing:

  • Heavily developed areas with land uses that handle hazardous chemicals.
  • Recent well construction activities or repairs. MassDEP recommends taking a bacterial test after any well repair or pump or plumbing modification, but only after disinfection and substantial flushing of the water system.
  • Contaminant concentrations above state or federal standards found in earlier testing.
  • Noticeable variations in quality, such as a water quality change after a heavy rain, extended drought, or an unexplained change in a previously trouble-free well (i.e. funny taste, cloudy appearance, etc.)

When taking any sample, MassDEP recommends that it be taken after a heavy rainstorm. These events tend to highlight conditions of improper well construction or poor soil filtration.

What should the water be tested for?

First contact your Board of Health to see if there are any specific water quality tests required by the local Private Well Regulation. MassDEP recommends that the well owner test for, at a minimum, the parameters listed in the EPA pamphlet Protect Your Family: A Guide to Water Quality Testing for Private Wells.You should test initially for all contaminants of concern, and then at a minimum of once every ten years (except for bacteria and nitrate/nitrite, which should be sampled yearly), or as otherwise required by the local Board of Health.

Where can the water get tested?

MassDEP recommends the use of a state certified analytical laboratory for all water quality testing. Local Private Well Regulations may specify the use of a state certified lab. A searchable list of MassDEP certified labs can be found at: https://eeaonline.eea.state.ma.us/DEP/Labcert/Labcert.aspx. See the link below for instructions on how to use this database.

Additional Resources

Who pays for water testing?

The private well owner is responsible for the costs of the water quality analyses. As testing fees may vary between certified labs, it may be worthwhile to compare costs between labs.

What can contaminate a well?

Some contaminants are naturally occurring from features found in the rocks and soils of Massachusetts. These include substances like bacteria, radon, arsenic, uranium, and other minerals.

Other contaminants find their way onto the land from human activities. On a large scale, industrial/commercial activities, improper waste disposal, manure storage, road salting, and fuel spills can introduce hazardous substances to the ground. Typical residential activities, such as the application of fertilizers and pesticides, fueling of lawn equipment, and disposal of household chemicals can contaminate the ground when done improperly. Even an on-site residential septic system can pose a threat to your well.

Contact for FAQs - Private Wells

Help Us Improve Mass.gov with your feedback