Manganese in New Jersey well water
In New Jersey, 20% of 141,293 private wells tested between 2002 and 2024 had manganese above the New Jersey nuisance level (50 ug/L), according to NJDEP.
Manganese stains fixtures and laundry above 50 ug/L. EPA's health advisory is 300 ug/L; infants are the most sensitive, and newer research links elevated manganese to neurological effects in children. It is one of the most common private well problems in New England.
Check your manganese number
Type the value from your lab report. It is compared to the New Jersey nuisance level and the EPA limit, the same way the full interpretation does it.
Getting it fixed
Book a free in-home water test with a licensed local company, or see the treatment guide for what removes manganese.
By county, from homeowner tests
Share of private wells above the state guidance level (50 ug/L) in tests homeowners sent to the state lab, 2002 to 2024.
| County | Wells tested | Above state level | Highest | |
|---|---|---|---|---|
| Cape May | 7,348 | 48% | ||
| Monmouth | 7,582 | 39% | ||
| Middlesex | 1,222 | 28% | ||
| Sussex | 14,793 | 26% | ||
| Passaic | 5,838 | 25% | ||
| Mercer | 3,471 | 23% | ||
| Burlington | 12,189 | 21% | ||
| Essex | 231 | 21% | ||
| Salem | 5,094 | 21% | ||
| Morris | 13,112 | 19% | ||
| Ocean | 9,095 | 17% | ||
| Cumberland | 8,423 | 15% | ||
| Warren | 7,035 | 15% | ||
| Camden | 3,759 | 14% | ||
| Gloucester | 9,218 | 14% |
Towns with the highest share above the state level
- Old Bridge township, Middlesex County83% of 41 wells
- Florence township, Burlington County79% of 157 wells
- Logan township, Gloucester County76% of 72 wells
- Robbinsville township, Mercer County73% of 158 wells
- Hamilton township, Mercer County72% of 196 wells
- Eastampton township, Burlington County67% of 58 wells
- Chesterfield township, Burlington County64% of 281 wells
- Moorestown township, Burlington County63% of 82 wells
- Monroe township, Middlesex County62% of 242 wells
- Upper Freehold township, Monmouth County61% of 923 wells
- Middle township, Cape May County60% of 2,238 wells
- Manalapan township, Monmouth County58% of 702 wells
- Oldmans township, Salem County57% of 221 wells
- West Cape May borough, Cape May County56% of 39 wells
- West Windsor township, Mercer County56% of 146 wells
- Frankford township, Sussex County54% of 1,000 wells
- Middletown township, Monmouth County54% of 63 wells
- Millstone township, Monmouth County54% of 1,608 wells
- Marlboro township, Monmouth County54% of 267 wells
- Elsinboro township, Salem County54% of 267 wells
- East Windsor township, Mercer County53% of 104 wells
- Cranbury township, Middlesex County52% of 96 wells
- Buena borough, Atlantic County50% of 46 wells
- East Brunswick township, Middlesex County50% of 30 wells
- Springfield township, Burlington County49% of 513 wells
Sources
- NJDEP Private Well Testing Act summaries: Share of private wells exceeding each standard in tests required at sale or lease under the New Jersey Private Well Testing Act, September 2002 to December 2024, published by NJDEP. Tests are untreated water at the time of sale or lease, so every well is counted once per transaction. Municipalities with fewer than ten wells are suppressed. Standards are New Jersey's: arsenic 5 ug/L, PFOA 14 ng/L, PFOS 13 ng/L, PFNA 13 ng/L, manganese and iron secondary standards. Uranium and PFAS were added to the required panel in 2021 and 2020, so their well counts are smaller. Retrieved September 9, 2026.
- Individual samples from the USGS Water Quality Portal and state monitoring, summarized per geography. manganese counts and shares are listed on each county and town page with their sources.