Well water in Sandoval County, New Mexico
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Testing strongly recommended
tested well samples in Sandoval County exceeded the EPA limit for arsenic (10 ug/L), based on public data from USGS Water Quality Portal.
1,538 test results across 15 contaminants from at least 228 wells, 1924 to 2023; chloride has the most at 270. Data refreshed September 15, 2026.
Compiled by Nick at Well Water Nerd from public records. How these pages are built
An estimated 34,955 people in Sandoval County get their drinking water from a private well, per USGS 2015 county water use. That is about 25% of residents.
Separately, the USGS national arsenic model estimates that 17% of the 34,955 people on private wells in Sandoval County draw water above 10 ug/L (the model's range is 12% to 21%), from geology and well depth rather than local tests.
What individual samples found
Each row summarizes every public sample for that contaminant inside Sandoval 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 |
|---|---|---|---|---|---|---|
| Arsenic 1972 to 2023 | 94 | 89% | 6 | 1,100 | 10 ug/L EPA limit | |
| Fluoride 1948 to 2023 | 213 | 100% | 0.62 | 16 | 4 mg/L EPA limit | |
| Nitrate 1924 to 2023 | 260 | 85% | 0.305 | 32 | 10 mg/L EPA limit | |
| Radium (226 + 228) 1974 to 2021 | 29 | 86% | 0.1 | 160 | 5 pCi/L EPA limit | |
| Uranium 1959 to 2023 | 68 | 93% | 3.04 | 42 | 30 ug/L EPA limit | |
| Lead 1972 to 2023 | 70 | 56% | 0 | 3,400 | 15 ug/L EPA limit | |
| Copper 1960 to 2023 | 68 | 72% | 0.001 | 0.55 | 1.3 mg/L EPA limit | |
| E. coli 2005 to 2014 | 18 | 0% | 0 | 0 | 0 MPN/100mL EPA limit | |
| PFOA 2020 to 2023 | 11 | 0% | 0 | 0 | 4 ng/L EPA limit | |
| PFOS 2020 to 2023 | 11 | 0% | 0 | 0 | 4 ng/L EPA limit | |
| Chloride 1924 to 2023 | no limit | 270 | 100% | 25.6 | 10,800 | 250 mg/L nuisance level |
| Iron 1924 to 2023 | no limit | 167 | 80% | 40 | 96,000 | 300 ug/L nuisance level |
| Sodium 1956 to 2023 | no limit | 141 | 100% | 110 | 6,300 | 20 mg/L health guideline |
| Manganese 1959 to 2023 | no limit | 107 | 72% | 1.92 | 2,000 | 300 ug/L health guideline |
| Radon 1993 to 2021 | no limit | 11 | 91% | 300 | 410 | 2,000 pCi/L health guideline |
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 | 4%181 samples | 7%46 samples | 0%25 samples | n/a |
| Fluoride | 6%176 samples | 0%23 samples | 0%10 samples | n/a |
| Arsenic | 32%57 samples | 48%23 samples | 30%10 samples | n/a |
| Lead | 3%33 samples | 0%23 samples | 0%10 samples | n/a |
| Uranium | 3%31 samples | 0%23 samples | 0%10 samples | n/a |
| Copper | 0%31 samples | 0%23 samples | 0%10 samples | n/a |
Nitrate above the limit in Sandoval County fell from 7% of 46 samples in the 2000s to 0% of 25 in the 2010s.
Fluoride above the limit in Sandoval County fell from 6% of 176 samples before 2000 to 0% of 23 in the 2000s.
Arsenic above the limit in Sandoval County rose from 32% of 57 samples before 2000 to 48% of 23 in the 2000s.
Lead, uranium, copper 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 addressWhat this means
The contaminants most often above their limit here are arsenic (34% of 94 samples), fluoride (5% of 213 samples), and nitrate (4% of 260 samples). A well next door can differ sharply from yours because bedrock fractures, well depth and plumbing all matter, so these rates describe the area, not your tap.
Chloride, Iron, and Manganese are widespread in local groundwater. They are mainly a staining and taste problem, but high manganese also carries a health advisory for infants.
What to test for in Sandoval County
- 1Arsenic34% of 94 local samples were above the limit.
- 2Fluoride5% of 213 local samples were above the limit.
- 3Nitrate4% of 260 local samples were above the limit.
- 4Radium (226 + 228)3% of 29 local samples were above the limit.
- 5Uranium1% of 68 local samples were above the limit.
- 6Lead1% of 70 local samples were above the limit.
- 7Coliform bacteriaRecommended for every private well, every year.
Test your Sandoval County well for arsenic, fluoride and 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
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 Mexico: certified labs, state programs and prices.
Already have results back? Get your lab report read against the Sandoval County numbers, $29. Every line explained, ranked by what matters, with the fix for each.
The rock under Sandoval County
Not a principal aquifer
The USGS map places this area outside any principal aquifer, which usually means wells here draw from fractured bedrock or thin local deposits rather than a large regional aquifer. Bedrock wells of that kind are where arsenic, radon and uranium turn up, and yields vary from well to well.
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 Mexico
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, NMED
- Laboratory Certification, NMED
Contamination sources on record in Sandoval County
NMED storage tank facilities and landfills records 47 regulated sites in Sandoval County, among 47 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.
- 45
- registered underground storage tank sitesRegistered tanks are regulated and inspected; they matter most when they are old or near a shallow well.
- 2
- lined landfills and transfer facilities
Treatment that fits the local profile
Arsenic
Point-of-use reverse osmosis; Adsorptive media (iron-based) whole-house; Anion exchange
Fluoride
Point-of-use reverse osmosis; Activated alumina; Distillation
Nitrate
Point-of-use reverse osmosis; Anion exchange; Distillation
Radium (226 + 228)
Water softener (cation exchange); Point-of-use reverse osmosis
Uranium
Point-of-use reverse osmosis; Anion exchange; Whole-house anion exchange
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 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.
For lead
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 lead
Acid neutralizing filter
whole-house, at the point of entry, about $1,200
Raises pH so plumbing stops leaching lead and copper.
Free, no obligation
Get on the list for a free in-home water test in Sandoval County
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Common questions
Is there arsenic in well water in Sandoval County?
Arsenic was detected in 89% of 94 public well samples in Sandoval County, and 34% 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 high is radon in well water in Sandoval County?
The median radon level across 11 public samples in Sandoval County was 300 pCi/L, with a high of 410 pCi/L. New Hampshire recommends treatment above 2,000 pCi/L.
How often should I test a private well in Sandoval 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.
Counties near Sandoval 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 Mexico dataset as CSV, every county and town, with the sources named.
Sources
- USGS Water Quality Portal: 1,538 samples in Sandoval 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.
- USGS national arsenic model (Ayotte 2017): estimated share of 34,955 people on private wells in Sandoval 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.
- NMED storage tank facilities and landfills: 47 regulated sites located in Sandoval County. Underground storage tank facilities and permitted landfills from the New Mexico Environment Department. Retrieved September 18, 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.