privatewelldata / States / Virginia / Nitrate
Nitrate in well water in Virginia
3% of 1,394 sampled wells in Virginia had nitrate above the EPA limit of 10 mg/L (as nitrogen) (latest result per well, 36 counties, samples 1906–2026). The highest county share was Northampton County: 21% of 112 wells. Data updated 2026-10-18.
of sampled wells above 10 mg/L (as nitrogen)
wells with a result
counties with data
counties where 1 in 4+ wells were above
Nitrate in wells most often comes from fertilizer, manure and septic systems, so shallow wells near fields or septic fields are more exposed, and levels can change with the seasons. Only a lab test shows it. Federal limits apply to public water systems; a private well is the owner's responsibility to test (EPA).
% of sampled wells above the EPA limit (latest result per well; counties with 10+ wells). Source: USGS/EPA Water Quality Portal, 2026-10-18 · privatewelldata.com
Nitrate by county in Virginia
| County | Above 10 mg/L (as nitrogen) | Median | 90th pct. | Years |
|---|---|---|---|---|
| Northampton County | 21% of 112 | 0.985 mg/L as N | 14 | 1954–2025 |
| Rockingham County | 12% of 50 | 4.251 mg/L as N | 10.8 | 1970–2022 |
| Caroline County | 10% of 58 | 0.101 mg/L as N | 8.833 | 1970–2025 |
| Culpeper County | 7% of 29 | 0.76 mg/L as N | 6.483 | 1980–2024 |
| Accomack County | 5% of 97 | 0.19 mg/L as N | 6.325 | 1906–2026 |
| Southampton County | 5% of 22 | 0.021 mg/L as N | 0.136 | 1938–2023 |
| Fairfax County | 3% of 32 | 0.455 mg/L as N | 2.9 | 1976–2015 |
| Clarke County | 3% of 37 | 3.4 mg/L as N | 6.6 | 1986–2014 |
| Virginia Beach City | 3% of 39 | 0 mg/L as N | 0.012 | 1979–2015 |
| York County | 1% of 73 | 0 mg/L as N | 0.2 | 1940–2019 |
| Prince William County | 1% of 128 | 0.325 mg/L as N | 1.8 | 1968–2015 |
| James City County | 0% of 92 | 0.009 mg/L as N | 0.23 | 1946–2026 |
| Suffolk City | 0% of 70 | 0.113 mg/L as N | 0.95 | 1929–2026 |
| Buchanan County | 0% of 61 | 0.04 mg/L as N | 0.91 | 1978–2017 |
| King William County | 0% of 52 | 0.023 mg/L as N | 0.08 | 1941–2021 |
| Chesapeake City | 0% of 37 | 0 mg/L as N | 0.023 | 1970–2026 |
| Isle of Wight County | 0% of 37 | 0.023 mg/L as N | 0.24 | 1969–2023 |
| Surry County | 0% of 35 | 0.023 mg/L as N | 0.113 | 1942–1998 |
| Sussex County | 0% of 30 | 0.004 mg/L as N | 0.19 | 1937–2022 |
| Northumberland County | 0% of 29 | 0.136 mg/L as N | 0.339 | 1918–2018 |
| New Kent County | 0% of 28 | 0.05 mg/L as N | 0.09 | 1969–2023 |
| Loudoun County | 0% of 26 | 0.525 mg/L as N | 4.3 | 1970–2014 |
| Charles City County | 0% of 25 | 0.05 mg/L as N | 0.07 | 1969–2021 |
| Westmoreland County | 0% of 25 | 0.023 mg/L as N | 0.203 | 1933–2022 |
| Hanover County | 0% of 20 | 0.05 mg/L as N | 0.25 | 1943–2014 |
| Fauquier County | 0% of 17 | 0.13 mg/L as N | 2.937 | 1980–2019 |
| Gloucester County | 0% of 17 | 0.09 mg/L as N | 2 | 1906–2021 |
| Lancaster County | 0% of 15 | 0.181 mg/L as N | 0.37 | 1918–1998 |
| Henrico County | 0% of 14 | 0.06 mg/L as N | 0.14 | 1947–2007 |
| Middlesex County | 0% of 14 | 0.09 mg/L as N | 0.181 | 1918–2022 |
| Newport News City | 0% of 14 | 0.009 mg/L as N | 0.19 | 1942–2026 |
| Floyd County | 0% of 13 | 0.339 mg/L as N | 2.56 | 1963–2000 |
| King and Queen County | 0% of 13 | 0.08 mg/L as N | 0.23 | 1943–2022 |
| Carroll County | 0% of 12 | 0.312 mg/L as N | 0.91 | 1963–2014 |
| Richmond County | 0% of 11 | 0.17 mg/L as N | 0.34 | 1918–1977 |
| Augusta County | 0% of 10 | 0.788 mg/L as N | 4.21 | 1979–2022 |
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Download this table (CSV) · public-domain source data: Water Quality Portal (USGS, EPA, NWQMC). How we calculate these numbers.
How Virginia compares
Share of sampled wells above the EPA nitrate limit in each state we cover (states with 100+ wells).
| # | State | Above 10 mg/L (as nitrogen) |
|---|---|---|
| 1 | California | 10% of 16,344 |
| 2 | Pennsylvania | 8% of 6,478 |
| 3 | Minnesota | 6% of 7,259 |
| 4 | North Carolina | 5% of 1,964 |
| 5 | New York | 5% of 6,236 |
| 6 | Massachusetts | 4% of 2,556 |
| 7 | New Jersey | 4% of 3,915 |
| 8 | Wisconsin | 4% of 3,666 |
| 9 | Virginia | 3% of 1,394 |
| 10 | Maine | 2% of 726 |
| 11 | Michigan | 2% of 1,970 |
| 12 | Ohio | 1% of 1,239 |
| 13 | New Hampshire | 0% of 1,685 |
Where to test: official lab list for Virginia
About this data
- Each well counts once, using its latest nitrate result in the Water Quality Portal (siteType = Well), downloaded 2026-10-18.
- Results reported as "not detected" count as below the limit. Results far outside the plausible range are withheld for review, not shown.
- Sampled wells include monitoring and research wells, not only household wells, and are not a random sample, so the share is a guide to local risk, not a rate for all homes.
- The limit is the EPA maximum contaminant level for public water systems (EPA).
Questions
Is nitrate common in Virginia well water?
In our data, 48 of 1,394 sampled wells in Virginia (3%) had a latest nitrate result above the EPA limit of 10 mg/L (as nitrogen), across 36 counties. That ranks Virginia 9 of 13 states we cover for this share.
Which Virginia counties have the most wells above the nitrate limit?
Among counties with at least 10 sampled wells: Northampton County (21%, 23 of 112 wells); Rockingham County (12%, 6 of 50 wells); Caroline County (10%, 6 of 58 wells).
Does this tell me whether my well is safe?
No. These are past results from wells sampled by USGS, EPA and state programs, including monitoring wells, and levels differ from well to well. The only way to know your water is to test your own well at a certified lab.
How do I test my well for nitrate in Virginia?
Order a nitrate test from a lab on Virginia's official certified-lab list (linked on this page) and ask for its bottles and sampling instructions. Our test helper suggests what else to test for at the same time.
What should I do if my nitrate result is above 10 mg/L (as nitrogen)?
Retest to confirm, use another water source for drinking and cooking while you sort it out, and look at certified treatment options. Our guide walks through each step with sources.