Guide · Updated September 9, 2026

Uranium in Maine Well Water

Uranium in a Maine bedrock well does not announce itself. At the concentrations private wells actually see, you do not get a reliable taste, smell, or color cue in the glass. The number that counts is a certified-lab result in µg/L. Until that sheet is in your hand, a town map, a neighbor story, or a treatment catalog is not a diagnosis.

This page is a reading order for that sheet. It is not a medical consult and not a shopping list.

What the comparison numbers mean

Maine CDC’s private-well summaries use a Maximum Exposure Guideline (MEG) of 30 µg/L for uranium. The Maine Tracking Network MEG table lists that same 30 ug/L figure. The Maine CDC uranium tip sheet is plainer: a result of 30 ug/L or higher is too much uranium for drinking and for making drinks.

The tip sheet also splits cooking use at 130 ug/L. Between 30 and 130 ug/L it says do not drink the water and do not use it to make coffee, tea, juice, or infant formula; cooking and other household uses are still listed. Above 130 ug/L it adds soups, stews, and cooking dried foods (rice, beans, oatmeal, pasta) to the “do not use” list; brushing teeth, bathing, dishes, and garden use remain listed. That is the tip sheet’s use split. It is not a diagnosis of your health, and this page will not turn it into one. If the number is high or you are not sure you understand the sheet, call Maine CDC Toxicology — 866-292-3474 (toll-free in Maine) or 207-287-4311, TTY Maine Relay 711, or email ehu@maine.gov — or start at wellwater.maine.gov.

EPA’s public-system Maximum Contaminant Level (MCL) for uranium is also 30 µg/L (30 ppb, or 0.030 mg/L) under the Radionuclides Rule. Same concentration as Maine’s MEG. Different legal world. That MCL applies to public water systems, not to a private well. Maine’s Drinking Water Program radionuclides page is the public-system rule. Your well is unregulated. 30 µg/L is the MEG / comparison number, not a private-well legal limit.

EPA’s private-well pages and CDC’s testing guidance say the same structural fact: you own the test schedule. Maine CDC’s private-well page is explicit — owners are responsible for testing.

How often Maine CDC says to test

On the Maine CDC private-well page:

• Every year: total coliform, E. coli, nitrate, nitrite.
• Every 3–5 years: arsenic, chloride, copper, fluoride, hardness, iron, lead, magnesium, manganese, pH, radon, sodium, uranium.

Bacteria or nitrate on the same sheet is a health-department problem first. Do not start with a uranium tank while coliform is still open.

A statewide paper is not your well

Yang, Smitherman, Hess, Culbertson, Marvinney, and Zheng published “Uranium and Radon in Private Bedrock Well Water in Maine” in Environmental Science & Technology (USGS publication 70108159). Statewide they compiled 5,857 private bedrock-well samples. About 6.9% of those samples were above 30 µg/L. In the greater Augusta subset, 53 of 1,093 samples — about 4.8% — were above 30 µg/L.

Read those percentages as a published convenience sample, not as a town ranking. The dataset is owner-submitted / Health and Environmental Testing Laboratory style work. People who already worry, or who live near a known granite belt, are more likely to mail a bottle. Maine Tracking Network’s private-well maps warn that uranium hot-spot towns may over-test, so a town’s percent-above-guideline can be biased upward. This page will not rank towns. Your well is not a map.

Get a certified-lab µg/L — not a store-kit guess

Start at this site’s Maine certified-lab inventory. Accreditation is by analyte. A coliform certificate is not a uranium certificate. Confirm uranium (or gross alpha / radionuclides, if that is the method the lab uses) on the current certificate before you pay.

Sample the untreated kitchen cold tap unless the lab’s chain-of-custody says otherwise. If you already have treatment, say so on the form and ask whether they want a raw-side tap.

Units. µg/L and ppb are the same magnitude for uranium in water. 0.030 mg/L = 30 µg/L. If the sheet prints mg/L, convert before you compare it to the MEG. How to read a well water lab report is the decoder. Store kits on well-water test kits are screens. They do not replace a certified uranium number.

Nationwide lab index: certified labs by state. Maine lab news (hours, bottle kits, closings) lives at /labs/maine/news.

After the sheet: classes, not a catalog

Maine CDC’s uranium tip sheet frames treatment as point-of-use (under the kitchen sink, for drinking and cooking) versus point-of-entry (whole house). That is a use decision, not a shopping list.

The treatment classes commonly named for uranium in drinking water are reverse osmosis and anion exchange (ion exchange). Name the class after you have a µg/L. Then look the model up in the NSF drinking-water treatment-unit database for the contaminant and the flow you actually need. This page does not rank brands.

Order after the pressure tank still matters. Iron, hardness, and sediment can foul a membrane or an anion bed. Treatment order after the pressure tank is the sequence page. Do not buy a uranium stage to “cover” a rusty tap you have not tested.

Maine Drinking Water Program technical assistance — April Bledsoe, 207-215-7124, april.bledsoe@maine.gov — can talk through treatment types, sampling, and well questions. That is not the same desk as Toxicology. Toxicology interprets whether the number is “too much.” DWP helps you talk about hardware class. Neither one is a brand referral.

Mail-in certified-lab kits

Tap Score / SimpleLab is an approved class example of a mail-in certified-lab kit — not a ranked pick. If a kit lands in your mailbox, it is still a screen or a mail-in panel until a certified method and a µg/L are on the report. Pair it with a lab from /labs/maine. Bacteria or nitrate still goes to the health department.

Paid-relationship rules for this site: disclosure.

What to do this week

1. Open /labs/maine. Confirm uranium (or the radionuclide method the lab lists) on the certificate.
2. Sample untreated kitchen cold. Ask the lab about bottle type and hold time.
3. Put the µg/L next to 30. If the sheet is at or above 30, use the tip sheet’s drinking / cooking split and call Toxicology if the number is high or unclear.
4. If bacteria or nitrate is also flagged, call the health department before you shop a uranium stage.
5. Only after the sheet: decide point-of-use versus point-of-entry, then reverse osmosis or anion exchange, then NSF lookup — in that order.

Updated 2026-09-09.