You can’t taste it, smell it, or see it — and roughly one in ten Maine wells has too much of it.
More than half of Maine households get their drinking water from a private well, and according to data from the Maine Tracking Network, about one in every ten of those wells contains arsenic above the standard set for public water supplies. That number climbs even higher in parts of central and southern Maine, where bedrock geology naturally releases arsenic into groundwater. And right now — mid-summer, when water tables drop and wells work harder than at any other point in the year — is exactly when arsenic concentrations in well water can quietly rise.
Why Arsenic Shows Up in Maine Wells
Arsenic in Maine well water isn’t usually the result of pollution or a spill. It occurs naturally in the fractured bedrock that most drilled wells in Maine and New Hampshire draw from. As groundwater moves through that rock, it picks up dissolved arsenic along the way. Two neighboring homes can have completely different results — one well fine, the other well several times over the limit — because the water is traveling through different fractures.
What makes arsenic different from many other water problems is that it gives you no warning. Water with elevated arsenic looks, smells, and tastes completely normal. There’s no staining, no odor, no cloudiness. The only way to know is a laboratory test. Long-term exposure matters: arsenic is a known human carcinogen, and ongoing consumption has been linked to increased risk of cardiovascular disease and other chronic health effects. Maine’s Maximum Exposure Guideline for arsenic in private wells is 10 micrograms per liter — the same threshold used for public water systems.
Why Summer Makes It Worse
Summer is peak demand season for private wells — lawns, gardens, guests, camps, and long showers after a day on the lake. At the same time, dry stretches lower the regional water table. When a well’s water level drops, the pump draws from deeper in the well, and as the well recovers it can pull in sediment and minerals that normally stay put. Contaminants that come from bedrock — arsenic, uranium, and other metals — can become more concentrated as water levels fall. A well that tested fine two or three years ago in April may look different in a hot, dry July.
What Maine Homeowners Should Do
- Test for arsenic at least every three to five years, and any time you buy a home, drill or deepen a well, or notice a major change in water level or usage. Maine CDC also recommends testing annually for coliform bacteria and nitrates.
- Don’t rely on your senses. Unlike iron or sulfur problems, arsenic produces no taste, smell, or staining. A normal-seeming glass of water tells you nothing.
- Know the rules if you’re a landlord. Maine law (Title 22, §2660-Y) requires residential landlords whose buildings are served by private wells to test the water for arsenic and provide results to tenants.
- Expect it in a real estate transaction. Arsenic is a standard component of well water panels requested by buyers, agents, and lenders across Maine and New Hampshire. An elevated result doesn’t kill a deal — treatment is well established — but an untested well can stall one.
If a test comes back high, the fix is straightforward. Point-of-use reverse osmosis systems and whole-house treatment both handle arsenic effectively — but treatment should always be sized and verified against an actual lab result, not a guess.
What Chanalytical Tests For
Chanalytical Laboratories runs arsenic as part of its standard well water panels, alongside the other tests Maine well owners most often need: coliform bacteria and E. coli, nitrates and nitrites, uranium and other metals, radon in water, and PFAS panels for households concerned about forever chemicals. Whether you need a single arsenic result or a full panel for a home purchase, the lab work is done locally in Maine with fast turnaround.
For Home Inspectors
Summer is the busiest season for real estate in Maine, and water results are often the last item holding up a closing. Chanalytical works with home inspectors across the region to keep transactions moving: local drop-off, quick turnaround on standard well panels, and clear, professional reports you can hand directly to agents and buyers. If arsenic or another parameter comes back elevated, the report gives everyone at the table a concrete number to work from.
For Water Treatment Companies
Arsenic treatment lives or dies on verification. Chanalytical supports treatment professionals with baseline testing before system design, post-installation verification to confirm removal performance, and periodic follow-up testing to document that systems keep doing their job — especially important in summer, when changing water levels can shift influent chemistry. Clean lab data protects your installation and your customer relationship.
Get Your Well Tested Before Summer’s Over
If your well hasn’t been tested for arsenic in the last few years — or ever — this is the season to do it. Chanalytical Laboratories is a Maine-based water testing lab offering fast turnaround, convenient sample drop-off, and direct support for homeowners, home inspectors, real estate professionals, and water treatment companies. Visit Chanalytical.com to order a test kit or find out which panel fits your situation.