What's in Calvert County, MD tap water?
Calvert County sits about 40 miles from our Arlington base and is served primarily by Prince Frederick, which provides water to roughly 4,370 people. It draws from the Coastal-plain aquifers. Maryland's Eastern Shore and Southern Maryland sit on coastal-plain aquifers. That groundwater commonly carries naturally occurring arsenic and radionuclides, iron and manganese, and nitrate from farming, with saltwater intrusion a growing concern near the Chesapeake Bay.
Find a local installerPrince Frederick water quality report, explained
What testing of Prince Frederick water shows for Calvert County, compared with EWG's health guidelines. Being above a guideline is not a legal violation.
Primary water system (EPA)
Prince Frederick
Serves about 4,370 people
Contaminants EWG most often flags above its health guidelines for the Coastal-plain aquifers:
Larger areas have more than one water system. Enter your exact zip code below for your utility's own EPA record and EWG report.
Measured by the EPA · Calvert County, MD
Calvert County, MD runs its own water system — and it has not been tested for PFAS.
Calvert County draws its water from the ground rather than from a river, through a small system serving about 4,371 people. Well water arrives with whatever the rock it sat in put into it, and small systems test less often than large ones.
Groundwater does not carry the chlorination byproducts that dominate river supplies, because it needs far less disinfection. What it carries instead comes out of the rock: arsenic, radium, manganese, and nitrate where there is farming above the aquifer. Boiling concentrates all of them rather than removing them.
It was tested for 29 PFAS compounds in the EPA's latest round and none came back above reporting limits — genuinely good news, and a single window in time. No lead or copper results appear in EPA's published record for this system. It carries 5 violations on file, none health-based — monitoring and reporting lapses rather than contamination.
Prince Frederick, on the EPA's record
- Source
- groundwater
- Connections served
- 1,561
- People served
- 4,371
- Violations on file
- 5, none health-based
How this water is treated before it reaches you
Treatment makes water safe to distribute. It is not designed to remove PFAS, and chlorine-based disinfection creates byproducts of its own.
Source: EPA Safe Drinking Water Information System record for Prince Frederick (PWSID MD0040011). Systems outside the UCMR5 sample are not required to test for PFAS.
5 contaminants above EWG's health guidelines
Everything EWG found above its guideline in Calvert County's water, from testing in 2018-2023. A level can be under the legal limit and still be listed here: EWG's guidelines are set to protect health, not to be easy to meet.
| Contaminant | In this water | EWG guideline | Times over |
|---|---|---|---|
| Arsenic | 7.41 ppb | 0.004 ppb | 1,852× |
| Total trihalomethanes (TTHMs) | 11.1 ppb | 0.15 ppb | 74× |
| Haloacetic acids (HAA9) | 3.20 ppb | 0.06 ppb | 53× |
| Haloacetic acids (HAA5) | 2.70 ppb | 0.1 ppb | 27× |
| Radium, combined (-226 and -228) | 0.33 pCi/L | 0.05 pCi/L | 6.5× |
Source: EWG Tap Water Database, Chesapeake Ranch Estates (MD0040004).
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Common in U.S. tap water
Calvert County water quality FAQ
Is Calvert County, MD tap water safe to drink?
Public water in Calvert County meets federal EPA legal limits. But "legal" is not the same as "clean": across the Coastal-plain aquifers, independent testing routinely finds contaminants like arsenic (naturally occurring) and radium & radionuclides (naturally occurring) above EWG's stricter health guidelines. Enter your zip code above to see your exact utility's record.
What contaminants are common in Calvert County water?
For the Coastal-plain aquifers, the contaminants that most often exceed health guidelines are arsenic (naturally occurring), radium & radionuclides (naturally occurring), nitrates (agricultural runoff), PFAS (forever chemicals) and total trihalomethanes (where chlorinated). Your specific levels depend on your utility, which you can look up by zip code above.
Does Sanavia install reverse osmosis systems in Calvert County?
Yes. Calvert County is roughly 40 miles from our Arlington base and inside our service area. A Sanavia Hydra reverse osmosis system installs under your sink and reduces every contaminant class above, and we'll mail you a free water test kit.
Where does Calvert County tap water come from?
Calvert County's primary public water system is Prince Frederick, which serves roughly 4,370 people. It sits in the Coastal-plain aquifers, so its water shares that region's contaminant profile. Larger areas may have more than one utility, so enter your exact zip code above for your own system's EPA record.
Is well water in Calvert County tested for these contaminants?
No. Private wells are not covered by municipal testing, so the responsibility falls on the homeowner. If your Calvert County home is on a well, nitrate and naturally occurring contaminants are worth testing for specifically, and a reverse osmosis system reduces them at the tap. We'll mail you a free water test kit either way.
Contaminants common in the Coastal-plain aquifers
Each of these is a plain-English guide to a contaminant class common in Calvert County and the surrounding Coastal-plain aquifers — what it is, the health context, and what actually removes it.
Reverse osmosis in Prince Frederick & Calvert County, MD
Prince Frederick treats this water to the federal standard, yet the contaminants listed above still exceed EWG’s stricter health guidelines — Arsenic (naturally occurring), Radium & radionuclides (naturally occurring), Nitrates (agricultural runoff) and 2 more. Most of them either pass straight through treatment or form after the plant, in the pipes between it and the tap, which is why the fix has to be at the tap as well.
PFAS is the reason a carbon pitcher is not enough here. The compounds do not break down, they are measured in parts per trillion, and the federal limit that covers them is not enforceable until 2029. A reverse osmosis membrane is one of the few things at household scale that reduces them rather than passing them through.
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Full testing record for Calvert County · Find a local installer
Detailed city water reports
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