Well water in the Portland metro
Greater Portland splits in two at the water line. Portland, South Portland, and Westbrook mostly drink Sebago Lake water delivered by the Portland Water District, which supplies roughly one in six Maine residents (Portland Water District). Drive 15 minutes out, and the pipes stop. In Gorham, Falmouth, Cumberland, and the outer edges of Scarborough, homes leave the district and run on private wells drilled into fractured bedrock. No agency inspects those wells. Testing and treatment are entirely the owner's call.
The geology under that suburban-rural edge is not neutral. A USGS assessment of more than 11,000 Maine wells identified southern coastal Maine as one of the state's clusters of elevated arsenic, alongside central Kennebec County and the Ellsworth area (USGS study coverage; the full report is USGS SIR 2010-5199). Statewide, about one in 10 wells exceeds the 10 ug/L federal arsenic standard, and in 44 Maine towns more than 25 percent of sampled wells exceeded it. Arsenic has no taste, smell, or color. The regional pattern is exactly why a Cumberland County well deserves a lab test rather than a guess.
The commuter-town blind spot
The metro's well owners are often first-time well owners: households that moved from a city water bill in Portland to a drilled well in Gorham or Falmouth without ever thinking about it. City water arrives tested. Well water arrives as-is. Maine CDC's cadence is the fix: coliform bacteria and nitrates every year, then arsenic, uranium, radon, and fluoride every three to five years (Maine CDC testing guidance). The well water testing page covers labs, kits, and costs, and if a purchase is in motion, the home-buying guide lists what to test before closing.
What metro test results tend to flag
Arsenic is the headline risk given the southern coastal cluster, and the arsenic treatment page explains the two standard fixes: point-of-use reverse osmosis at the kitchen tap, or a whole-house system when the number runs high. Radon and uranium ride in the same granite-influenced bedrock statewide, so they belong on the same lab order. Iron and manganese are the everyday complaints, staining fixtures and laundry long before anything else shows. Town-by-town arsenic context lives on the Maine arsenic data page.
How the match works here
Tell us your town and what prompted the question: a purchase, a stain, a test result. We connect you, free, with an independent local professional who tests or treats wells around Greater Portland for a living. The professional quotes the work and does the work. Other regions, from the Sebago lakes region next door to the rest of the state, are on the service areas page.
Towns served in this region: Portland, South Portland, Westbrook, Gorham, Falmouth, Cumberland, and Scarborough.