Septic systems, fertilizer, and low summer water tables can all push nitrate higher — and nitrate gives you no warning you can taste or smell.
More than half of Maine residents get their drinking water from a private well, and none of those wells are on a required testing schedule. State groundwater data shows nitrate levels have been rising across many parts of Maine, with the usual sources being septic systems, livestock waste, and nitrogen fertilizer applied to farm fields and lawns.
July is when all three of those sources are working at full capacity. Lawns and fields got their fertilizer in late spring. Septic systems are handling peak household loads — summer guests, camps and cottages back in use after nine months idle, more laundry, more showers. And by mid-summer the water table has dropped, which means whatever reaches groundwater is diluted by less of it.
That combination is why a nitrate result from March and a nitrate result from July can look like they came from two different wells.
What Nitrate Is, and Why It Belongs on Your Test
Nitrate is a nitrogen compound that moves easily through soil and into groundwater. It does not settle out, it is not filtered by depth the way some contaminants are, and it does not change how water looks, smells, or tastes. A well can sit above the health guideline for years while the water at the tap seems completely normal.
Maine CDC sets a Maximum Exposure Guideline for nitrate at 10 mg/L, matching the federal drinking water standard. The concern behind that number is infants. Babies under six months who consume water high in nitrate — most often in reconstituted formula — can develop methemoglobinemia, commonly called blue baby syndrome, in which the blood’s ability to carry oxygen is reduced. It develops quickly and it is a medical emergency.
There is a second reason nitrate earns its place on a standard panel: it is a tracer. Nitrate at an elevated level usually means something from the surface is reaching your well. If septic effluent or barnyard runoff is finding a path into the water, bacteria can travel that same path. A nitrate hit is often the first quantitative sign that a wellhead, casing, or nearby leach field needs attention — well before anyone gets sick.
What Maine and New Hampshire Homeowners Should Actually Do
The baseline recommendation for private wells across the Northeast is straightforward: test annually for total coliform bacteria and nitrate, and run a broader chemistry panel every three years. That baseline moves up in a few specific situations.
- Someone in the house is pregnant, nursing, or under six months old. Test before the water is used for formula, not after.
- Any work was done on the septic system. Installation, replacement, pumping, or repair can all temporarily affect nearby wells.
- Heavy rain, drought, flooding, or nearby excavation. Any of these changes how water moves underground.
- New neighbors, new construction, or a new agricultural operation upgradient. Land use changes show up in water chemistry.
- You are buying or selling. Do not wait for the inspection contingency clock to start.
Summer timing matters more than most people expect. University of New Hampshire research found bacteria levels in private wells run highest during warm stretches — meaning a clean winter result does not describe your well in July. If you have only ever tested in the cold months, you have never seen your well under stress.
For real estate transactions in Maine and New Hampshire, this is not optional. FHA and VA loans on properties with private wells require water testing, and nitrate and nitrite sit on that required list alongside bacteria and lead. A result that comes back late, or comes back positive with no time left to retest, delays closings.
What Chanalytical Tests For
Chanalytical Laboratories runs the panels Maine and New Hampshire well owners actually need:
- Nitrate and nitrite — including the levels required for FHA and VA transactions
- Total coliform and E. coli — the standard bacteria screen
- Arsenic, uranium, lead, manganese, and other metals — common in Northeast bedrock wells
- Radon in water — a persistent concern in New England granite
- PFAS panels — for homeowners near known contamination areas or with sludge-spreading history nearby
- Standard well chemistry — pH, hardness, iron, sodium, chloride, TDS
- Commercial and multi-property programs — for inspectors, treatment companies, landlords, and camps
Samples can be dropped off directly, and results come back with the numbers laid out clearly enough to act on.
For Home Inspectors
Water results are one of the most common reasons a transaction stalls. Working with a Maine-based lab means shorter shipping time, faster turnaround, and someone local to call when a client has a question about a number on the page. Reports are formatted so you can hand them to a buyer, an agent, or a lender without translating them first. If a result comes back needing a retest, you find out early enough that it does not blow the closing date.
For Water Treatment Companies
Independent lab data is what makes a treatment recommendation defensible. Baseline testing before installation documents the problem you were hired to solve. Post-installation verification proves the system is doing what you said it would. Periodic follow-up catches media exhaustion, resin fouling, or a failing UV lamp before the customer does. For nitrate specifically, verification matters — reverse osmosis and anion exchange both reduce nitrate, but only measurement tells you whether the unit installed is keeping up with the load.
Test Before the Summer Ends
If your well has not been tested this year — or has only ever been tested in cold weather — this is the season to get a real picture of it. Nitrate and bacteria are inexpensive to measure and impossible to detect any other way.
Chanalytical Laboratories is Maine-based, with drop-off sampling, fast turnaround, and dedicated support for home inspectors and water treatment companies across Maine and the Northeast. Visit Chanalytical.com to get started or to ask which panel fits your property.