Well water in Monmouth County, New Jersey

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Testing recommended

private wells tested between 2002 and 2024 in Monmouth County had total coliform above the New Jersey limit (any detection), according to NJDEP.

The strongest signal is PFOA: 46% of 24 local samples were above the limit, too few samples to carry the headline but first on the test list below.

7,586 private wells tested 2002 to 2024 in state summaries; 1,667 test results across 14 contaminants from at least 180 wells, 1926 to 2026; sodium has the most at 398. Data refreshed September 15, 2026.

Compiled by Nick at Well Water Nerd from public records. How these pages are built

An estimated 50,298 people in Monmouth County get their drinking water from a private well, per USGS 2015 county water use. That is about 8% of residents.

Separately, the USGS national arsenic model estimates that 4% of the 50,298 people on private wells in Monmouth County draw water above 10 ug/L (the model's range is 2% to 5%), from geology and well depth rather than local tests.

What homeowner tests found

NJDEP Private Well Testing Act summaries: private wells tested and reported to the state, 2002 to 2024. Shares are against the level the state applies to each contaminant, named in the last column; several are stricter than EPA.

Contaminant	Above state level	Wells tested	State level
Iron	74%	7,582	300 ug/L
Manganese	39%	7,582	50 ug/L
Total coliform	11%	7,572
Gross alpha	2%	6,917	15 pCi/L
PFOA	1%	677	14 ng/L
E. coli Fecal coliform or	<1%	7,568
Nitrate	<1%	7,586	10 mg/L
Arsenic	<1%	2,136	5 ug/L
PFOS	<1%	677	13 ng/L
PFNA	<1%	677	13 ng/L

What individual samples found

Each row summarizes every public sample for that contaminant inside Monmouth County. Above limit means above the EPA maximum contaminant level; where EPA has no enforceable limit, the row shows a health guideline or nuisance level instead.

Contaminant	Above limit	Samples	Detected	Median	Highest	Limit
PFOA 2021 to 2024	46%	24	58%	2.55	16	4 ng/L EPA limit
PFOS 2021 to 2024	13%	23	48%	0	10	4 ng/L EPA limit
Lead 1977 to 2024	7%	191	49%	0	200	15 ug/L EPA limit
Radium (226 + 228) 2000 to 2012	4%	26	92%	0	5.1	5 pCi/L EPA limit
Nitrate 1973 to 2026	1%	214	34%	0	20.9	10 mg/L EPA limit
Arsenic 1977 to 2025	0%	153	45%	0	2.6	10 ug/L EPA limit
Uranium 2008 to 2012	0%	12	67%	0.01	0.145	30 ug/L EPA limit
Sodium 1926 to 2025	no limit	398	100%	3.5	8,120	20 mg/L health guideline
Iron 1926 to 2025	no limit	307	91%	5,200	527,000	300 ug/L nuisance level
Manganese 1957 to 2025	no limit	302	97%	112	12,400	300 ug/L health guideline

Sampled fewer than 10 times, too few to summarize: Copper (3), Fluoride (3), Radon (6), Chloride (5).

Over time

Share of samples above the limit by period. A cell needs ten samples to show; a comparison needs twenty in each period. Later periods sample fewer wells, and often the ones already known to have a problem.

Contaminant	before 2000	2000s	2010s	2020s
Nitrate	0%108 samples	0%36 samples	4%46 samples	4%24 samples
Lead	13%97 samples	0%24 samples	0%46 samples	0%24 samples
Arsenic	0%13 samples	0%45 samples	0%54 samples	0%41 samples
Radium (226 + 228)	n/a	0%16 samples	10%10 samples	n/a

Nitrate, lead, arsenic have held within a few points between the two most recent periods with enough samples.

Closer than the county

See the sampled wells near your address

The same records, drawn around one point: which wells within a few miles were sampled and what they found, how deep the wells next to you were drilled, and any leaking tank or cleanup site within a mile.

Check my address

What this means

Among homeowners in Monmouth County who sent a sample to the state lab, the health-based limits most often exceeded were total coliform (11% of 7,572 wells), PFOA (1% of 677 wells), and E. coli (<1% of 7,568 wells). These are ordinary wells tested by their owners, so the shares are the best available picture of a typical well here, with one caveat: people test more often when they suspect a problem.

Iron and manganese exceed the state's advisory level in a sizable share of wells; these are mostly a taste, staining or diet issue rather than a toxicity one.

What to test for in Monmouth County

1
PFOA
46% of 24 local samples were above the limit.
2
PFOS
13% of 23 local samples were above the limit.
3
Total coliform
11% of 7,572 local wells tested were above the New Jersey limit (any detection).
4
Lead
7% of 191 local samples were above the limit.
5
Radium (226 + 228)
4% of 26 local samples were above the limit.
6
Nitrate
1% of 214 local samples were above the limit.
7
E. coli
<1% of 7,568 local wells tested were above the New Jersey limit (any detection).
8
Arsenic
<1% of 2,136 local wells tested were above the New Jersey limit.
9
Volatile organic compounds (VOCs)
9 hazardous waste sites on record locally.
10
Metals panel
9 hazardous waste sites on record locally.

Test your Monmouth County well for PFOA, PFOS and total coliform

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 $209 Already tested? Upload the report

Just want bacteria checked first? Tap Score coliform and E. coli test, $99. Coliform and E. coli are the tests every well needs every year.

Want a quick look before paying for a lab? Home well water test strips on Amazon check hardness, iron, pH and nitrate in minutes. They are a screen, not a result: arsenic, bacteria, uranium and PFAS need a certified lab.

Affiliate links: the merchant pays us a commission and the price is the same for you. It does not change what the data above says. As an Amazon Associate we earn from qualifying purchases.

Where to get a well tested in New Jersey: certified labs, state programs and prices.

Already have results back? Get your lab report read against the Monmouth County numbers, $29. Every line explained, ranked by what matters, with the fix for each.

The rock under Monmouth County

Northern Atlantic Coastal Plain aquifer system

Semiconsolidated sand. Coastal plain sands like these give steady yields at moderate depth. Salt water and sodium are the usual issues near the coast, and nitrate where the water table is shallow; arsenic and radon from bedrock are less common.

Classification from the USGS Principal Aquifers of the United States (national map, 2003 edition, GIS release 2015), read at the county centroid. A single well can sit in a different unit, especially near a boundary.

Official help in New Jersey

Two places to start that are not selling anything: the state program that answers private well questions, and its list of labs certified to run drinking water tests. A certified lab is the difference between a result you can act on and a number.

Private Wells, NJDEP
Certified Laboratories, NJDEP

Contamination sources on record in Monmouth County

NJDEP records 9 hazardous waste sites in Monmouth County, among 3,319 regulated sites in total. Groundwater does not follow property lines, so a well within a few hundred feet of one of these is worth testing for what that site could release.

9: hazardous waste sitesSolvents, degreasers and metals from industrial sites can travel far in fractured bedrock.
2,546: registered underground storage tank sitesRegistered tanks are regulated and inspected; they matter most when they are old or near a shallow well.
26: lined landfills and transfer facilities
738: other remediation projects

Treatment that fits the local profile

Total coliform

Inspect and repair the well cap and casing, then shock chlorinate and retest; UV disinfection whole-house; Chlorination system

Iron

Oxidizing filter whole-house; Water softener (low levels); Aeration plus filtration

Manganese

Oxidizing filter (greensand, birm) whole-house; Water softener (low levels); Point-of-use reverse osmosis

PFOA

Granular activated carbon whole-house; Point-of-use reverse osmosis; Anion exchange

PFOS

Granular activated carbon whole-house; Point-of-use reverse osmosis; Anion exchange

Lead

Point-of-use reverse osmosis; Certified lead-removal carbon filter; Neutralizing filter to raise pH and stop leaching

Systems we would look at first

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 total coliform

Aquasana Rhino Well Water with UV

whole-house, at the point of entry, about $2,871

Whole-house system built for wells: sediment pre-filter, KDF and carbon, and a UV lamp rated to kill 99.99% of bacteria and viruses. It does not remove arsenic, nitrate, uranium or radon.

For iron

Iron and manganese oxidizing filter

whole-house, at the point of entry, about $1,800

Air-injection or greensand media; fixes staining at the source.

For PFOA

Under-sink reverse osmosis system

under-sink or countertop, about $300

Look for NSF/ANSI 58 certification listing the contaminant you need removed.

For PFOA

Whole-house PFAS carbon system

whole-house, at the point of entry, about $3,000

Granular activated carbon certified to NSF/ANSI 53 for PFOA and PFOS; replace media on schedule.

For PFOA

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.

For PFOS

Aquasana Claryum 3-Stage under-sink filter

under-sink or countertop, about $175

Certified to NSF/ANSI 53 to reduce 99% of lead and 99.7% of PFOA and PFOS at the tap. Not a fix for arsenic, nitrate or bacteria.

For PFOS

Aquasana HealthShield whole-house filter

whole-house, at the point of entry, about $2,099

Whole-house carbon system the maker certifies to reduce PFAS (PFOA and PFOS) and VOCs at every tap; a UV option adds bacteria protection.

Free, no obligation

Get on the list for a free in-home water test in Monmouth County

No water treatment company serves Monmouth County through Well Water Nerd yet. We are signing licensed companies on county by county: they test at your tap for free, walk you through the numbers, and quote treatment only if something needs fixing. Leave your details and you are first in line. Nothing is shared until a company joins for Monmouth County, and you get an email naming it first.

Common questions

Is there arsenic in well water in Monmouth County?

Arsenic was detected in 45% of 153 public well samples in Monmouth County, and 0% were above the EPA limit of 10 ug/L. Arsenic has no taste or smell; a lab test is the only way to know your level.

How often should I test a private well in Monmouth County?

Test for bacteria and nitrate every year. Test once for arsenic, uranium, radon, fluoride, manganese and PFAS, then again every three to five years or after any change in taste, color, or plumbing.

Towns in Monmouth County

42 towns have fewer than 30 public samples and are included in the Monmouth County totals above rather than shown separately: Aberdeen township, Allenhurst borough, Allentown borough, Asbury Park, Atlantic Highlands borough, Avon-by-the-Sea borough, Belmar borough, Bradley Beach borough, Brielle borough, Deal borough, Eatontown borough, Englishtown borough, Fair Haven borough, Farmingdale borough, Freehold borough, Hazlet township, Highlands borough, Holmdel township, Interlaken borough, Keansburg borough, Keyport borough, Lake Como borough, Little Silver borough, Loch Arbour village, Long Branch, Manasquan borough, Matawan borough, Monmouth Beach borough, Neptune City borough, Neptune township, Oceanport borough, Ocean township, Red Bank borough, Roosevelt borough, Rumson borough, Sea Bright borough, Sea Girt borough, Shrewsbury borough, Shrewsbury township, Spring Lake borough, Spring Lake Heights borough, West Long Branch borough.

Counties near Monmouth County

Closest first. Groundwater does not stop at a line on a map, so the next county over is a fair second opinion.

Want the numbers themselves? Download the New Jersey dataset as CSV, every county and town, with the sources named.

Sources

USGS Water Quality Portal: 1,667 samples in Monmouth County. Data from the Water Quality Portal, a service of USGS, EPA and USDA; groundwater samples collected by USGS and cooperators. Retrieved September 3, 2026.
NJDEP Private Well Testing Act summaries: summaries for 10 contaminants in Monmouth County, up to 7,586 wells each. 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.
USGS national arsenic model (Ayotte 2017): estimated share of 50,298 people on private wells in Monmouth County above 10 ug/L of arsenic, from geology, well depth and land use. County estimates of domestic well users with arsenic above 10 ug/L from the USGS national logistic regression model (Ayotte, Medalie and Qi, 2017), with private well population from the USGS 2015 county water-use compilation (Dieter and others, 2018). Retrieved September 15, 2026.
NJDEP regulated sites: 3,319 regulated sites located in Monmouth County. Known Contaminated Sites, regulated underground storage tank facilities and solid waste landfills from the New Jersey Department of Environmental Protection (NJ-GeoWeb). Retrieved September 9, 2026.

Non-detects count as samples and are treated as zero when computing medians. Exactly at the limit counts as not above it. A sample belongs to the town containing the well's reported coordinates.