Nitrate in Pennsylvania well water
In Pennsylvania, 4% of 8,840 private wells tested between 2007 and 2025 had nitrate above the EPA limit (10 mg/L), according to the Penn State water testing lab.
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 EPA limit and the EPA limit, the same way the full interpretation does it.
Test your Pennsylvania 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 Pennsylvania: 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, 2007 to 2025.
| County | Above state level | Wells tested | Highest |
|---|---|---|---|
| Lancaster | 403 | 30.1 mg/L | |
| Blair | 81 | 73.4 mg/L | |
| Franklin | 119 | 15.4 mg/L | |
| York | 382 | 33.1 mg/L | |
| Northumberland | 68 | 22 mg/L | |
| Lawrence | 35 | 12.5 mg/L | |
| Lebanon | 48 | 18.2 mg/L | |
| Berks | 200 | 19.4 mg/L | |
| Cumberland | 144 | 22.1 mg/L | |
| Union | 146 | 14.7 mg/L | |
| Mifflin | 183 | 13.4 mg/L | |
| Mercer | 132 | 12.2 mg/L | |
| Chester | 211 | 15.5 mg/L | |
| Bedford | 128 | 18.2 mg/L | |
| Juniata | 195 | 17.3 mg/L |
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 |
|---|---|---|---|---|---|
| Lancaster | 4,942 | 98% | 12 | 443 mg/L | |
| Blair | 162 | 99% | 12 | 321 mg/L | |
| Northampton | 60 | 97% | 7.55 | 109 mg/L | |
| Berks | 352 | 91% | 4.83 | 109 mg/L | |
| Lebanon | 265 | 95% | 5.9 | 181 mg/L | |
| York | 307 | 97% | 5.3 | 121 mg/L | |
| Northumberland | 266 | 86% | 6.59 | 94.6 mg/L | |
| Cumberland | 326 | 95% | 5.5 | 68.4 mg/L | |
| Lehigh | 196 | 98% | 3.87 | 50 mg/L | |
| Montgomery | 258 | 98% | 4.08 | 59.6 mg/L | |
| Chester | 2,695 | 92% | 3.58 | 199 mg/L | |
| Juniata | 43 | 95% | 2.5 | 44 mg/L | |
| Delaware | 81 | 90% | 3.5 | 35 mg/L | |
| Mifflin | 66 | 94% | 2.8 | 67.9 mg/L | |
| Clinton | 113 | 81% | 0.35 | 218 mg/L |
- Ephrata township, Lancaster County93% of 1,003
- Earl township, Lancaster County84% of 111
- North Woodbury township, Blair County82% of 79
- Leacock township, Lancaster County77% of 70
- Upper Leacock township, Lancaster County69% of 48
- Caernarvon township, Lancaster County65% of 1,268
- Lower Oxford township, Chester County63% of 46
- East Lampeter township, Lancaster County63% of 46
- Oley township, Berks County54% of 80
- West Pennsboro township, Cumberland County52% of 44
- West Fallowfield township, Chester County51% of 49
- East Earl township, Lancaster County47% of 75
- West Lampeter township, Lancaster County46% of 1,698
- Salisbury township, Lancaster County40% of 102
- Paradise township, Lancaster County38% of 48
- Myerstown borough, Lebanon County35% of 49
- Kennett township, Chester County34% of 128
- West Marlborough township, Chester County34% of 35
- Providence township, Lancaster County34% of 38
- East Nottingham township, Chester County30% of 46
Sources
- Penn State Agricultural Analytical Services Lab drinking water summaries: County summaries of private water samples tested by the Penn State Agricultural Analytical Services Laboratory since 2007, published by the College of Agricultural Sciences. Counts are samples, not distinct wells. Shares are against the standard the lab prints: the EPA maximum contaminant level, or the secondary standard for iron, manganese and chloride. Lead is the first-draw result. Medians printed as 0.00 are stored as null because the lab rounds to two decimals. Retrieved September 16, 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.