By mid-August a Maine well sits at the low point of its year. The Maine Geological Survey puts the normal annual swing at about 3 to 4 feet and notes that levels “decline during the summer and fall as available precipitation is consumed by evapotranspiration processes.” About half of Maine’s residents draw household water from a private well, so this is most of the state at once.
When the table drops you draw from a different part of the aquifer than you did in May. On our bench in Gorham, the number that moves most quietly in late summer is manganese, and it is the one homeowners are least likely to have measured.
The numbers, and who publishes them
Manganese occurs naturally in New England bedrock. The Maine CDC states plainly that “elevated levels of manganese can occur in private wells nearly everywhere in Maine.”
- 0.05 mg/L. The EPA secondary standard, where you start to see “black to brown color; black staining; bitter metallic taste.” EPA does not enforce secondary standards. They describe nuisance, not risk.
- 0.3 mg/L. The EPA lifetime health advisory, set in its 2004 Drinking Water Health Advisory for Manganese and carried on the Maine CDC page. Guidance, not a legal limit for a private well.
- 1 mg/L. The one-day and ten-day advisory for the general population.
- Infants under 6 months. EPA recommends applying the 0.3 mg/L lifetime value even to a 10-day exposure, because formula carries substantially more manganese than breast milk and young infants absorb more and excrete less.
Two honest qualifiers. None of that is enforceable on a private well, and the science on long-term low-level exposure is still developing. We are a lab, not your doctor. We report the number; what it means for your household is a question for your health care provider. One practical note: boiling does not help. The Maine CDC is direct. “Boiling water will not destroy or remove manganese.”
What happens to the bottle after you fill it
The bottles are not interchangeable
Most of what decides whether a result is good happens before the sample reaches an instrument. A metals bottle arrives with acid already in it. The acid holds dissolved metals in solution so manganese and iron do not quietly plate out onto the plastic wall on the drive down. A bacteria bottle holds a little sodium thiosulfate to neutralize residual chlorine so it cannot keep killing organisms after collection. Rinsing a bottle before filling it, which feels like the careful thing to do, pours the preservative down the drain and ruins the sample. Do not rinse them.
Chain of custody is a piece of paper that does real work
The form asks for the address, the tap sampled, the date, the collection time, and your signature. Collection time is the field people leave blank, and the one we cannot invent. Without it we cannot show the sample ran inside its hold time, and an unprovable result is not a result.
Hold time is a clock that starts in your kitchen
For bacteria the working window is roughly 30 hours from the moment you fill the bottle to the start of analysis. Not from when we open the cooler. That is why we keep bacteria kits inside Maine and New Hampshire. No cross-country package beats that clock.
Manganese is the forgiving one. Acid-preserved metals hold far longer, so a metals sample rarely dies of time. Rejections are usually one of five things: no collection time recorded, a preserved bottle that was rinsed, air space in a bottle meant to be filled to the shoulder, a warm cooler, or a bacteria sample past its window. We call rather than run it. A bad number is worse than none.
Turnaround is set by prep and QC, not by the machine
The instrument reading takes minutes. The digestion, the calibration curve, and the batch QC take the day. Every batch carries blanks, spikes, and duplicates. If QC fails, the batch reruns and your sample goes with it. That is why an honest lab quotes a range rather than a date.
What you can do yourself, for free
- Check the toilet tank, the dishwasher, and white laundry. Black or brown-black staining points toward manganese. Rusty orange points to iron.
- Know that staining by itself is an aesthetic finding, not a health result. Nobody needs to sell you anything to interpret a stain.
- Check the date on your last full test. The Maine CDC recommends bacteria and nitrate annually, and a broader panel including manganese, arsenic, uranium, radon, lead, and fluoride every 3 to 5 years. Inside that window with nothing changed, you are current. Skip it.
- Read the Maine CDC private well water pages directly. Free, from the issuing body, better than any lab’s marketing.
The Maine CDC also names moments that warrant a test regardless of the calendar: expecting a baby, a change in smell, taste, or color, a well that runs dry and comes back, buying a home, installing or servicing treatment equipment, and any work on the well. Two of those are August events. The recovered dry well is one. The new baby is the other, and that is where the manganese number carries real weight.
If you decide to test
Chanalytical Laboratories is an independent third-party lab in Gorham. We are fast and accurate, and candid about the two things we cannot bend, hold time and chain of custody. Manganese is reported on our arsenic and metals panel. If your annual coliform check is overdue, bacteria testing is the one with the tight clock, so collect on a weekday morning. A general well water test covers the routine panel. Kits go out within Maine and New Hampshire. If you would rather hand the bottles to a person, we publish our drop-off locations, and collection questions are answered on our water testing FAQ. Test at the low point of the year and you learn what your well does at its worst.