Walnut Grove No 1
What EPA’s and CDC’s records show in this utility’s water: nitrate, arsenic and other regulated chemicals; lead and copper; and violations since 2016, with the certification that handles each result.
- Serves
- 290 people
- Connections
- 115
- Water source
- Groundwater
- Based in
- Rockville, VA
- County
- Hanover
- Owner
- Private
The ZIP code it serves
The short answer
Nothing in EPA’s and CDC’s records for this utility is above a health goal. That covers nitrate, arsenic and other regulated chemicals, plus lead and copper, not everything. No health-based violations on file since 2016.
What was found
Arsenic and uranium: Virginia’s yearly averages per water system, as CDC’s Environmental Public Health Tracking Network publishes them, 2021.
Total trihalomethanes (TTHM), haloacetic acids (HAA5), fluoride, chromium (total) and nitrate: EPA’s compliance monitoring file, samples taken from Jan. 11, 2012 to Jan. 28, 2019. Newer results are in the utility’s annual water quality report.
Below EPA’s limits3
Total trihalomethanes (TTHM)
Forms or is added in treatment
30.1ppb
Highest yearly average, 2013 to 2018
2018 average: 1.4 ppb
Averaged by year, the highest was 30.1 ppb, in 2013, below EPA’s legal limit of 80 ppb. Its highest single sample was 90.2 ppb. In 2018, the latest year on file, its two samples averaged 1.4 ppb. EPA recorded no violation for total trihalomethanes (TTHM) at this utility from 2012 to 2019.
What handles it
- NSF/ANSI 53 look for “Trihalomethanes (TTHM) Reduction”
- NSF/ANSI 58 look for “Trihalomethanes (TTHM) Reduction”
Haloacetic acids (HAA5)
Forms or is added in treatment
5.8ppb
Highest yearly average, 2013 to 2018
2018: not found
Averaged by year, the highest was 5.8 ppb, in 2013, below EPA’s legal limit of 60 ppb. Its highest single sample was 11.6 ppb. In 2018, the latest year on file, it wasn’t found in any of its two samples.
What handles it
No certification claim covers this compound yet.
Fluoride
Forms or is added in treatment
0.3ppm
Highest yearly average, 2012 to 2018
Averaged by year, the highest was 0.3 ppm, in 2018, below EPA’s legal limit of 4.0 ppm. That was also the latest year on file.
What handles it
- NSF/ANSI 58 look for “Fluoride Reduction”
- NSF/ANSI 53 look for “Fluoride”
5 compounds tested and not foundBelow the reporting level in every sample. Not found is not the same as zero.
- Arsenic
- Chromium (total)
- Lead
- Nitrate
- Uranium
Violations since 2016
No health-based violations on file with EPA since 2016.
What this report can’t tell you
Everything else. Arsenic and uranium results here are Virginia’s yearly averages as CDC publishes them, from 2021 on, with EPA’s national file for 2012 to 2019. Total trihalomethanes (TTHM), haloacetic acids (HAA5), fluoride, chromium (total) and nitrate come from EPA’s file alone, which ends in 2019. Walnut Grove No 1’s own annual report, which it must send you every year, has newer results for those and the contaminants this page does not show.
Your own plumbing. Lead results are the 90th percentile across homes the utility samples. Your home’s service line, solder and fixtures decide yours. A certified lab test is the only way to know.
What it means for your health. This page reports what the records show and EPA’s limits and goals; it is not medical advice. If you are worried about a health effect, talk to a doctor or your local health department.
Anything after the latest data. SDWIS data is from 2026 Q3; UCMR 5 didn’t sample this utility; CDC’s yearly averages for Virginia cover 2021; EPA’s compliance samples are from Jan. 11, 2012 to Jan. 28, 2019.
Testing your own tap
The 3 labs Virginia certifies closest to the area Walnut Grove No 1 serves, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.
Oakwood Scientific Laboratory
Mechanicsville, VA · about 7 miles
Certified for bacteria
Pole Green Drinking Water Laboratory
Mechanicsville, VA · about 7 miles
Certified for bacteria
Division of Consolidated Laboratory Services
Richmond, VA · about 12 miles
Certified for bacteria
Virginia Household Water Quality Program, Virginia Cooperative Extension: Drinking water clinics in about 70 counties a year, run through local Extension offices: pick up a kit, collect the sample on the set day, and drop it off locally. Each kit tests well, spring or cistern water for 28 things, including bacteria, nitrate, lead and arsenic. $70 a kit, with funding to help if you need it. Virginia Household Water Quality Program.
All 145 certified labs for VirginiaSources
- EPA UCMR 5 occurrence data, file of Oct. 15, 2026
- EPA SDWA bulk download (SDWIS federal data), 2026 Q3
- CDC Environmental Public Health Tracking Network, yearly averages Virginia supplied to CDC, 2021 to 2023, read Oct. 8, 2026. TapBuff’s comparisons with EPA’s limits are its own, not CDC’s or Virginia’s.
- EPA Six-Year Review 4 compliance monitoring data, 2012 to 2019, file of Feb. 5, 2024
- Certified labs: DCLS, drinking water laboratories with certification detail, read Oct. 10, 2026; distances from the Census 2020 ZIP code tabulation area gazetteer
- Limits and goals: each contaminant’s page, with its EPA source.
- How this page is built: methodology.
PWSID VA4085902. Rebuilt from EPA data on Oct. 18, 2026.
What to do next
- Nothing here is above a health goalIn EPA’s and CDC’s records for this utility. They don’t cover everything, which is why the next step matters.Every contaminant TapBuff tracks
- Get the utility’s own reportWalnut Grove No 1 must send you a water quality report every year. It covers contaminants this page does not show, and has newer results than EPA’s national file for the ones here that come from it.How to read it
- Test your own tap for leadYour service line, solder and fixtures decide the lead at your faucet, not the utility’s average.Lead in your water: what to do
- Decide if you want a filter at allA filter for taste or chlorine is a preference, not a need. The standards say what each kind can do.NSF/ANSI standards, decoded