Maine county well guide

Well Water in Knox County, ME: Testing, Contractors and Rules

About 6,314 households in Knox County, 40% of the county, rely on a private well. Nobody tests that water unless the owner does.

Labs within 40 milesLicensed contractors
40%of households on a private well
Share on wells, county vs state
Knox County40%
Maine average50%
13licensed contractors serve the county
21 mito the nearest certified lab, Bigelow Laboratory for Ocean Sciences
Nostatewide test required when a home is sold

Knox County has an estimated 6,314 households on private wells, 40% of the county. If you are one of them, testing, treatment and repairs are yours to arrange.

Local rules for wells in Knox County

Private wells in Knox County follow Maine's statewide rules, administered by Maine Water Well Commission, staffed by the Maine CDC Drinking Water Program. No water test is required by the state when a new well is completed. There is no statewide test requirement when a home is sold, though lenders often ask for one. The cards below show the details and the official sources.

At a glance

Water test for a new wellNot required statewide

No statewide water test and no state permit for a household well. The well must be drilled by a Maine licensed well drilling company using a licensed driller, to the Commission's construction rules (steel casing at least 20 ft and seated into bedrock, a sanitary cap, and a well cap above grade), and sited under the subsurface wastewater rules (100 ft from a septic disposal field, 50 ft from a septic tank). The driller files a well completion report with the Maine Geological Survey. A few towns require a bacteria test before a certificate of occupancy, and lenders usually do.

Water test when a home is soldNot required statewide

No statewide requirement. Maine's residential property disclosure form asks whether the water supply is a private well, when it was last tested and whether any test found a problem, so a recent test is expected in practice, and FHA, VA and USDA loans normally require a bacteria, nitrate and lead sample from an accredited lab before closing.

What the state recommends

Maine CDC recommends testing a private well every year for coliform bacteria and nitrate, and every three to five years for arsenic, uranium, radon, fluoride and manganese, the five contaminants Maine's bedrock wells carry most often (about one in ten wells is over the arsenic standard, and radon in water is higher in Maine than almost anywhere in the country). The standard Maine well water kit covers all of these plus lead, iron, hardness and pH. Test again after flooding, well work, hydrofracturing or a change in taste, color or smell.

Free or low-cost testingAvailable

No statewide free program, but a cheap and simple one: the state Health and Environmental Testing Laboratory in Augusta sells the standard well water kit through town offices, plumbing supply stores and by mail, with the bacteria, nitrate, arsenic, uranium, fluoride and metals panel for well under $100 and radon as an add-on, and Maine CDC explains the results. Several counties and tribal health programs run periodic free arsenic screening.

Getting your water tested near Knox County

4 certified labs within 40 miles serve Knox County, starting with Bigelow Laboratory for Ocean Sciences in East Boothbay (about 21 miles from the county center). Each card below shows whether the lab takes homeowner samples and which tests it is certified for.

4 certified labs within 40 miles

Licensed well contractors serving Knox County

13 licensed contractors serve Knox County, including Affordable Well Drilling Inc and Carmel Well Drilling Company LLC. Each profile carries the state license number and the date we checked it, and the filters below sort them by drilling, pump work or treatment.

Well depth and water chemistry

Wells in Knox County typically reach 180 to 330 feet; the median of 1,690 domestic wells in the Maine Geological Survey well database drilled since 2000 is 260 feet. What comes up with the water depends on the aquifer, and across Maine the usual suspects are arsenic (naturally occurring in bedrock across central and southern maine, worst in the augusta to bangor corridor and the midcoast), radon in water (granitic bedrock statewide, especially the southwest). A first full panel tells you which of them apply to your well.

Typical well depth

180 to 330 feet; the median of 1,690 domestic wells in the Maine Geological Survey well database drilled since 2000 is 260 feet

Contaminants to test for
  • Arsenic (naturally occurring in bedrock across central and southern Maine
  • Worst in the Augusta to Bangor corridor and the midcoast)
  • Radon in water (granitic bedrock statewide
  • Especially the southwest)
  • Uranium (granite in the same areas)
  • Manganese and iron (bedrock and overburden wells)
  • Fluoride (locally high in bedrock)
  • Coliform bacteria (dug wells and older drilled wells)
  • Hardness
  • Sodium and chloride (road salt near highways
  • Saltwater along the coast)
  • Nitrate (shallow wells in farm country
  • The Aroostook potato belt)
  • PFAS (near sludge-spread farmland in Fairfield and central Maine
  • And airfields)

Neighboring counties: Lincoln County, Waldo County, Kennebec County, Sagadahoc County.

What well work costs in Knox County

Basic bacteria and nitrate test$25 to $75lab fee, homeowner sample
Full panel lab test$150 to $400metals, VOCs, radiologicals
Well inspection$250 to $550flow, pressure, visual, water test
Submersible pump replacement$1,200 to $4,500parts and labor
Pressure tank replacement$400 to $1,200installed
Whole-house treatment system$800 to $6,000softener, iron filter, UV, RO
New well drilled$5,500 to $25,000about $25 to $65 per foot
Shock chlorination$80 to $300or about $20 as a DIY job

National ranges from published 2025 to 2026 contractor pricing. Local quotes vary with depth, access and materials.

Questions Knox County well owners ask

How many homes in Knox County are on a well?

About 6,314, or 40% of households, based on Census housing data and state well surveys. The share is highest outside the towns with public water.

Where is the closest certified lab to Knox County?

Bigelow Laboratory for Ocean Sciences in East Boothbay, about 21 miles away. Call first to ask whether they accept homeowner samples.

Do I need a permit to drill a well in Knox County?

No statewide water test and no state permit for a household well. The well must be drilled by a Maine licensed well drilling company using a licensed driller, to the Commission's construction rules (steel casing at least 20 ft and seated into bedrock, a sanitary cap, and a well cap above grade), and sited under the subsurface wastewater rules (100 ft from a septic disposal field, 50 ft from a septic tank). The driller files a well completion report with the Maine Geological Survey. A few towns require a bacteria test before a certificate of occupancy, and lenders usually do.

What does a well test cost near Knox County?

A bacteria and nitrate test runs $25 to $75 at most certified labs; a full panel with metals is $150 to $400. Mail-in kits cost about the same as walking in.