Arsenic is widespread in Sandoval County wells.
1 widespread, 1 worth checking, 4 rare out of 6 health checks.
From 34 wells tested in Sandoval County since 2003; your own well needs its own test. How to read this
Not charted, because fewer than 10 wells were tested: radon (5).
Rare: under 5%Worth checking: 5 to 15%Widespread: 15%+
Lab results: Water Quality Portal (USGS and EPA)
Who drinks from a well here
1 in 10 people 15,443 people
Nobody else tests these wells. Only you do.
People on wells: EPA researchers' 2020 estimate
How deep wells go here
Deep wells: fewer surface germs, more minerals from the rock.
Well depths: US Groundwater Well Database
Radon risk (a gas from rock)
Possible here. A home air test is inexpensive.
Radon zones: EPA map
Here's how Sandoval County compares with New Mexico and the counties around it.
Each result puts Sandoval County next to the 7 counties that border it, on the chart's 0 to 50% scale.
This one is widespread in Sandoval County wells.
Arsenic12 of 28 wells over
Too few tested to show: Los Alamos.
This one is worth checking in Sandoval County.
Manganese3 of 28 wells over
Too few tested to show: Los Alamos.
These 4 are rare in Sandoval County.
Uranium0 of 28 wells over
* Likely overstated, so we don't rank it.
Too few tested to show: Los Alamos.
Nitrate0 of 33 wells over
* Likely overstated, so we don't rank it.
Too few tested to show: Los Alamos.
Fluoride0 of 28 wells over
Lead0 of 28 wells over
Too few tested to show: Los Alamos.
Too few Sandoval County wells were tested for this one.
Radon in water5 wells tested
Coliform bacteria turned up in 1 of 22 tested Sandoval County wells, so test for it every year.
Coliform bacteria1 of 22 wells had it
Too few tested to show: Cibola, Los Alamos, McKinley, Rio Arriba, San Juan, Santa Fe.
E. coli0 of 23 wells had it
Too few tested to show: Cibola, Los Alamos, McKinley, Rio Arriba, San Juan, Santa Fe.
E. coli means human or animal waste is getting in, so if a test of your Sandoval County well finds it, boil drinking water until the well is fixed.
Iron reached staining levels in 0 of 27 tested wells, and it isn't a health risk.
Iron stains0 of 27 wells had it
Too few tested to show: Los Alamos.
Most of the 34 wells tested in Sandoval County were last tested before 2010.
An old result shows the water as it was then, so treat these 34 wells as a starting point and test your own.
Most Sandoval County wells in these records were tested for research or because someone suspected a problem, which can push the shares above what a typical home well would show (how we read the numbers).
One mail-in lab test covers the 4 things to check in Sandoval County.
- Bacteria
- Nitrate
- Arsenic
- Manganese
What New Mexico offers well owners
- Free testingNMED offers free well water screening at water fairs and limited free nitrate, iron and fluoride screening at some field offices; these do not replace certified lab tests. See the program
- Certified labsNew Mexico's list of certified labs
- Well recordsNew Mexico's well record search
Half the household wells here are shallower than 235 feet.
That comes from 7,220 household wells in New Mexico's drilling records. Most wells of every kind here are 150 to 390 feet deep. Wells as deep as Sandoval County's are usually better protected from fertilizer and bacteria at the surface, but they can pick up more of what's in the rock, like arsenic and uranium. Typical household wells here go deeper than in 23 of the 31 other New Mexico counties with enough drilling records.
Look up your own well's depth in New Mexico's well record search, or see how to find it.
Well depths: US Groundwater Well Database
Here's what we know about radon and PFAS in Sandoval County.
Sandoval County is in the EPA's middle radon zone. An indoor air test is cheap and tells you whether to look at your water. Radon guide
Between 2023 and 2025 the EPA had 3 town water systems in Sandoval County test for PFAS. None found any. Only 8 wells in Sandoval County have public PFAS results, so the town systems are the best clue to what's in the groundwater nearby. PFAS guide
Radon zones: EPA Map of Radon Zones. PFAS: EPA tests of town water systems, 2023 to 2025
Questions people ask about well water in Sandoval County
Is well water in Sandoval County safe to drink?
12 of 28 wells tested in Sandoval County had arsenic over the limit, about 4 in 10. Across New Mexico it's about 1 in 7. That's the highest share among the 15 New Mexico counties with 10 or more tested wells. So test your own well for arsenic before you count on it.
Can I get my well tested for free in Sandoval County?
NMED offers free well water screening at water fairs and limited free nitrate, iron and fluoride screening at some field offices; these do not replace certified lab tests. If not, use a lab New Mexico has certified for drinking water. Ask for bacteria, nitrate, arsenic and manganese, the tests that matter most in Sandoval County.
How deep are wells in Sandoval County?
Half the household wells here are shallower than 235 feet. Typical household wells here go deeper than in 23 of the 31 other New Mexico counties with enough drilling records.
How does Sandoval County compare with the counties around it?
For arsenic, the share of tested wells over the limit: Sandoval County, at 43%, had a higher share than all 6 neighboring counties with data. Groundwater doesn't stop at county lines, so Rio Arriba's 22% is worth knowing about if you live near it.
How often should I test my well in Sandoval County?
In Sandoval County, 1 of 22 tested wells had coliform bacteria, so the CDC's advice matters here: test for bacteria and nitrate every year, and right away after a flood, a repair, or any change in taste or smell.
If you buy something through our links, we may earn a commission. We'd recommend the same thing either way, and we'll tell you when a free option exists. How we make money
Where the Sandoval County numbers come from
- People on wells: 15,443 in Sandoval County, from EPA estimates built on the 2020 Census (Murray et al.).
- Lab tests: 290 well water samples from 34 wells in the Water Quality Portal, run by the USGS and EPA, 2003 to 2020.
- Well depths: 7,220 New Mexico drilling records for Sandoval County, gathered in the US Groundwater Well Database (Lin and others, 2024).
- Neighboring counties: the 7 counties that share a border with Sandoval County, from the Census Bureau's county adjacency file.
- PFAS: EPA tests of 3 town water systems in Sandoval County under the Fifth Unregulated Contaminant Monitoring Rule, 2023 to 2025.
- Radon: Sandoval County is zone 2 on the EPA Map of Radon Zones.
- State programs and links: Environment Department, checked November 1, 2026.