Nitrate in Maine well water
In Maine, <1% of 31,620 private wells tested had nitrate above the Maine guideline (10 mg/L), according to Maine CDC.
Nitrate reaches wells from fertilizer, septic systems and manure. Above the limit it can cause methemoglobinemia (blue baby syndrome) in infants under six months, and long-term exposure is associated with some cancers. Shallow and dug wells near farmland or dense septic systems are most at risk.
Check your nitrate number
Type the value from your lab report. It is compared to the Maine guideline and the EPA limit, the same way the full interpretation does it.
Test your Maine well for nitrate
Certified lab analysis of your own tap water, bottles and prepaid return shipping included. The Essential well panel covers arsenic, uranium, nitrate, lead, copper, manganese, iron, sodium and bacteria; radon and PFAS are add-ons.
Order the Tap Score well water test kit, from $209Already tested? Upload the report
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Systems that remove nitrate
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Some links below are affiliate links. If you buy through one, the merchant pays us a commission at no extra cost to you. It does not change which products we list or what the data says.
For nitrate
Under-sink reverse osmosis system
under-sink or countertop, about $300
Look for NSF/ANSI 58 certification listing the contaminant you need removed.
For nitrate
Aquasana SmartFlow reverse osmosis
under-sink or countertop, about $225
Certified to NSF/ANSI 58 and 53 to reduce arsenic (96%, pentavalent), fluoride (90%), lead (99%), nitrate, nitrite and PFOA/PFOS at the kitchen tap, with a remineralizer.
Rather have it installed and sized for your well? Book a free in-home water test with a licensed local company.
Where to get a well tested for nitrate in Maine: certified labs, state programs and prices.
By county, from homeowner tests
Share of private wells above the state guidance level (10 mg/L) in tests homeowners sent to the state lab, to .
| County | Above state level | Wells tested | Highest |
|---|---|---|---|
| Aroostook | 1,087 | ||
| Somerset | 1,097 | ||
| Penobscot | 3,022 | ||
| York | 2,517 | ||
| Franklin | 937 | ||
| Cumberland | 4,301 | ||
| Androscoggin | 1,541 | ||
| Lincoln | 2,107 | ||
| Kennebec | 5,242 | ||
| Oxford | 1,347 | ||
| Sagadahoc | 1,264 | ||
| Waldo | 1,654 | ||
| Knox | 799 | ||
| Hancock | 2,898 | ||
| Washington | 1,423 |
Towns with the highest share above the state level
- Fort Fairfield, Aroostook County15% of 47 wells
- Caribou, Aroostook County8% of 64 wells
- Houlton, Aroostook County7% of 44 wells
- Mapleton, Aroostook County7% of 45 wells
- Embden, Somerset County7% of 30 wells
- Palmyra, Somerset County5% of 56 wells
- Dexter, Penobscot County4% of 49 wells
- South Berwick, York County4% of 52 wells
- Canton, Oxford County3% of 30 wells
- Canaan, Somerset County3% of 62 wells
- Thorndike, Waldo County3% of 31 wells
- Corinna, Penobscot County3% of 65 wells
- Woodland, Aroostook County3% of 32 wells
- Troy, Waldo County3% of 32 wells
- Bradley, Penobscot County3% of 35 wells
- Albion, Kennebec County3% of 75 wells
- Garland, Penobscot County3% of 37 wells
- Verona Island, Hancock County3% of 37 wells
- Kennebunk, York County3% of 78 wells
- Newfield, York County3% of 39 wells
- Lagrange, Penobscot County3% of 40 wells
- New Sharon, Franklin County2% of 82 wells
- South Thomaston, Knox County2% of 42 wells
- Woodstock, Oxford County2% of 41 wells
- Hudson, Penobscot County2% of 44 wells
By county, from individual samples
Public monitoring samples against the EPA limit (10 mg/L); counties with at least 30 samples.
| County | Above EPA limit | Samples | Detected | Median | Highest |
|---|---|---|---|---|---|
| Cumberland | 915 | 89% | 1.24 | 162 mg/L | |
| Aroostook | 64 | 92% | 1.7 | 31 mg/L | |
| York | 142 | 68% | 0.05 | 29 mg/L | |
| Penobscot | 72 | 76% | 0.35 | 45 mg/L | |
| Oxford | 289 | 83% | 0.32 | 110 mg/L | |
| Androscoggin | 105 | 63% | 0.04 | 122 mg/L | |
| Kennebec | 139 | 45% | 0 | 39.7 mg/L | |
| Washington | 86 | 88% | 0.06 | 4.3 mg/L | |
| Somerset | 92 | 72% | 0.111 | 8 mg/L | |
| Franklin | 49 | 67% | 0.034 | 1.6 mg/L | |
| Hancock | 41 | 54% | 0.035 | 2.4 mg/L |
Sources
- Maine Tracking Network private well summaries: Town summaries of private well tests run by the Maine Health and Environmental Testing Laboratory, published by Maine CDC through the Maine Tracking Network. Shares are against Maine's guideline for each analyte (arsenic 10 ug/L, uranium 30 ug/L, fluoride 2 mg/L, manganese 0.3 mg/L, nitrate 10 mg/L, nitrite 1 mg/L). Towns with too few tests are suppressed (NR). Only the share above the guideline and wells tested are published; no medians. Retrieved September 3, 2026.
- Individual samples from the USGS Water Quality Portal and state monitoring, summarized per geography. nitrate counts and shares are listed on each county and town page with their sources.
Analysis: Nitrate in private wells, decade by decade, from the same public records.