District of Columbia Private Well Water Risk: Arsenic & Nitrate
These figures are USGS statistical estimates for private (domestic) wells in District of Columbia. They describe the area's modeled risk — not any single well.
Quick answer: County-level arsenic estimates are not available for District of Columbia in the USGS model. For nitrate, about 0% of District of Columbia's ~540 private-well residents are modeled above the 10 mg/L limit. The only way to know your own well is a certified lab test.
This is a modeled probability for the area, not a measurement of your well. USGS statistical models estimate how many private wells in this area are likely to exceed the federal limit — they cannot tell you what is in your water. Two neighbors can have very different results. The only way to know your well is to test it.
Nitrate
0%
of the private-well population is modeled above the 10 mg/L nitrate limit
~0
people on wells estimated above the limit
~540
total residents on private wells statewide
Source: USGS machine-learning nitrate model, Ransom et al. (2022), domestic-well depth zone.
Find out what's actually in your well
Private wells are not regulated by the EPA — nobody tests wells in District of Columbia for you. Arsenic, nitrate and coliform bacteria are the three most common private-well problems, and none of them has a taste or smell. A certified lab test checks all of them at once; the CDC and EPA recommend testing every well at least once a year.
Basic screening only. Confirm arsenic, nitrate and bacteria with a certified lab.
Find a certified drinking-water labAmazon links are affiliate links — we may earn a commission at no extra cost to you.
Arsenic
County-level arsenic estimates are not available for District of Columbia in the USGS conterminous-U.S. model.
Source: USGS domestic-well arsenic model, Lombard et al. (2021); county population product (2017).
Match the filter to your test result
Carbon pitchers and faucet filters do not remove arsenic or nitrate. Reverse osmosis is the point-of-use fix; a whole-house system handles the rest of the home.
APEC ROES-50 5-Stage Reverse Osmosis System
5-stage RO, ★ 4.7 — removes arsenic, nitrate, lead, fluoride and PFAS.
Check price on Amazon →Whole-house well water system
Treats every tap, shower and appliance — the right scale for sediment, iron, sulfur and bacteria on a private well.
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Under-sink RO removes arsenic, nitrate, lead and PFAS at the kitchen tap.
Shop on Waterdrop direct →Affiliate links — we may earn a commission at no extra cost to you. Re-test after installing to confirm the system is working.
District of Columbia well water: FAQ
How do I remove arsenic from well water in District of Columbia?
Test first. If arsenic is present, a point-of-use reverse-osmosis system under the kitchen sink removes 90%+ of it; boiling does not remove arsenic (it concentrates it), and carbon pitchers and water softeners do not remove it either. Whole-house adsorptive arsenic media is used when levels are high. Re-test after installing and then annually.
Is nitrate a problem in District of Columbia well water?
USGS models about 0% of District of Columbia's private-well population (~0 people) above the 10 mg/L nitrate limit. Nitrate is highest in shallow wells near fertilized cropland, septic systems or livestock, and matters most for infants and pregnancy.