Copper in well water

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private wells tested in Coos County, New Hampshire had copper above the limit, the highest share of any county, according to NH DHHS.

Copper leaches from pipes when water is acidic. Above 1.3 mg/L it causes stomach upset, and long-term exposure can harm the liver and kidneys. Blue-green stains on fixtures are the giveaway.

EPA limit: 1.3 mg/L (EPA action level (40 CFR 141.80))
Nuisance level: 1 mg/L
New Hampshire level: 1.3 mg/L
CAS number: 7440-50-8

Check your copper number

Type the value from your lab report. It is compared to the EPA limit, the same way the full interpretation does it.

Test your own well for copper

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

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Systems that remove copper

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For copper

Under-sink reverse osmosis system

under-sink or countertop, about $300

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

For copper

Acid neutralizing filter

whole-house, at the point of entry, about $1,200

Raises pH so plumbing stops leaching lead and copper.

Rather have it installed and sized for your well? Book a free in-home water test with a licensed local company.

Where copper is worst, by homeowner tests

Counties ranked by the share of private wells above the state guidance level in tests homeowners sent to the state lab. Shares combine town summaries, weighted by wells tested.

County	Above state level	Wells tested	Highest
Coos County, New Hampshire	15%	346	10.1 mg/L
Carroll County, New Hampshire	14%	1,488	18.2 mg/L
Hillsborough County, New Hampshire	14%	1,576	315 mg/L
Merrimack County, New Hampshire	13%	3,853	14.2 mg/L
Grafton County, New Hampshire	13%	1,939	58.1 mg/L
Cheshire County, New Hampshire	13%	372	12.3 mg/L
Strafford County, New Hampshire	11%	261	12.8 mg/L
Sullivan County, New Hampshire	11%	541	10.4 mg/L
Rockingham County, New Hampshire	11%	1,723	32.1 mg/L
Lincoln County, Wisconsin	11%	37	2.84 mg/L
Belknap County, New Hampshire	10%	1,379	15.8 mg/L
Trempealeau County, Wisconsin	7%	74	2.8 mg/L
Washburn County, Wisconsin	6%	31	1.41 mg/L
Sauk County, Wisconsin	6%	347	15.9 mg/L
Clark County, Wisconsin	6%	71	6.5 mg/L

By individual samples

Counties with at least 30 individual samples in public monitoring data, against the EPA limit.

County	Above EPA limit	Samples	Detected	Median
Calaveras County, California	55%	92	88%	3.05 mg/L
Gila County, Arizona	34%	904	53%	0.003 mg/L
Jackson County, Kansas	27%	125	75%	0.006 mg/L
Eddy County, New Mexico	14%	93	96%	0.012 mg/L
Silver Bow County, Montana	13%	635	79%	0.002 mg/L
Salt Lake County, Utah	6%	912	46%	0 mg/L
Moffat County, Colorado	5%	37	81%	0 mg/L
Beaver County, Utah	4%	205	18%	0 mg/L
Deer Lodge County, Montana	4%	125	92%	0.003 mg/L
Hillsborough County, New Hampshire	4%	85	71%	0.005 mg/L
Lyon County, Nevada	3%	89	38%	0 mg/L
Valencia County, New Mexico	3%	31	61%	0 mg/L
Vernon County, Louisiana	3%	63	84%	0.046 mg/L
Bon Homme County, South Dakota	3%	34	62%	0 mg/L
Carroll County, New Hampshire	3%	69	42%	0 mg/L

How to test

Use a state-certified lab and a proper sampling bottle; hardware-store strips cannot measure copper at the levels that matter. Collect from the kitchen tap before any treatment, and again after treatment if you install it.

How to treat

Neutralizing filter to raise pH
Point-of-use reverse osmosis