Arsenic in Colorado well water

In Colorado, 8% of 5,744 tested private well samples exceeded the EPA limit for arsenic (10 ug/L).

Arsenic occurs naturally in New England bedrock and dissolves into well water. Long-term exposure raises the risk of bladder, lung and skin cancers, and is linked to heart disease and lower IQ in children. It has no taste or smell, so testing is the only way to know.

Check your arsenic 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 Colorado well for arsenic

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 arsenic

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For arsenic

Under-sink reverse osmosis system

under-sink or countertop, about $300

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

For arsenic

Whole-house arsenic and uranium filter

whole-house, at the point of entry, about $2,500

Adsorptive iron-based media; sized to your well yield.

For arsenic

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 arsenic in Colorado: certified labs, state programs and prices.

By county, from individual samples

Public monitoring samples against the EPA limit (10 ug/L); counties with at least 30 samples.

County	Above EPA limit	Samples	Detected	Median	Highest
Prowers	64%	39	97%	20	2,690 ug/L
Bent	41%	125	98%	8	1,470 ug/L
Otero	35%	34	50%	1	950 ug/L
Montezuma	35%	55	67%	3.5	224 ug/L
Rio Blanco	27%	278	83%	3.6	150 ug/L
Saguache	26%	38	89%	3.25	150 ug/L
Garfield	23%	48	69%	2	1,100 ug/L
Montrose	21%	259	86%	1.7	333 ug/L
Alamosa	16%	43	100%	3	60 ug/L
Adams	16%	122	66%	1.3	37 ug/L
Eagle	13%	776	41%	0	2,800 ug/L
Archuleta	7%	88	50%	0.085	80 ug/L
Logan	6%	31	100%	2.3	16.4 ug/L
La Plata	4%	342	51%	0.55	61 ug/L
Douglas	3%	154	62%	1	87.5 ug/L

Lamar CCD, Prowers County68% of 37
McClave CCD, Bent County42% of 122
Ute Mountain CCD, Montezuma County40% of 45
Nucla CCD, Montrose County35% of 149
Commerce City CCD, Adams County26% of 61
Meeker CCD, Rio Blanco County26% of 263
Mosca-Hooper CCD, Alamosa County18% of 33
Minturn-Red Cliff CCD, Eagle County13% of 768
Bald Mountain CCD, Boulder County7% of 46
Ignacio CCD, La Plata County6% of 196
Sedalia CCD, Douglas County6% of 50
East Adams CCD, Adams County5% of 37
Montrose CCD, Montrose County5% of 38
South Aurora CCD, Arapahoe County3% of 35
Craig CCD, Moffat County3% of 75
Durango Southwest CCD, La Plata County3% of 77
Oak Creek CCD, Routt County2% of 41
Durango CCD, La Plata County2% of 49
Arboles CCD, Archuleta County2% of 59
Parker CCD, Douglas County2% of 62

Sources

Individual samples from the USGS Water Quality Portal and state monitoring, summarized per geography. arsenic counts and shares are listed on each county and town page with their sources.

Analysis: Arsenic in private wells, state by state, from the same public records.