What's in Frederick County, MD tap water?
Frederick County sits about 43 miles from our Arlington base and is served primarily by City of Frederick, which provides water to roughly 54,000 people. It draws from the Piedmont reservoirs, rivers & wells. Piedmont and northern-Maryland communities draw from a mix of reservoirs, rivers (including the Susquehanna and Monocacy) and groundwater wells. Chlorination byproducts plus agricultural and industrial runoff drive most of the contaminants that exceed EWG's health guidelines.
Find a local installerCity of Frederick water quality report, explained
What testing of City of Frederick water shows for Frederick County, compared with EWG's health guidelines. Being above a guideline is not a legal violation.
Primary water system (EPA)
City of Frederick
Serves about 54,000 people
Contaminants EWG most often flags above its health guidelines for the Piedmont reservoirs, rivers & wells:
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 · Frederick County, MD
Frederick County, MD tap water is fully legal.
It is also 5.5× the health standard for lead.
Frederick County is served by City of Frederick, a surface-water system supplying roughly 54,000 people. It treats its own water rather than buying it from a regional wholesaler, so what comes out of the tap is its work end to end.
Surface water needs heavy disinfection, and chlorine reacting with organic matter in the river is what creates trihalomethanes and haloacetic acids. Those are the contaminants that most often sit above health guidelines here, and they form in the pipes after treatment rather than at the plant.
Every federal limit that applies here is met. Those limits weigh what removal costs. EWG says its health standards are “based only on protecting health and does not consider technical feasibility or the cost of water treatment”. Here is how far apart the two are.
Harm to the brain and nervous system · EPA limit 10 ppb (action level, lowered from 15 ppb, in force November 2027)
Harm to fetal growth and child development · no federal limit exists
The EPA's latest round found 1 PFAS compound in this supply. Lead sampling put the ninetieth percentile at 1.1 ppb — meaning nine in ten homes tested below that, and one in ten above it. City of Frederick has 2 violations on file with the EPA, 1 of them health-based.
City of Frederick, on the EPA's record
- Source
- surface water
- Connections served
- 16,600
- People served
- 54,000
- Violations on file
- 2 (1 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.
Levels: EPA Fifth Unregulated Contaminant Monitoring Rule (UCMR5, 2023–2025) for PFAS, and the Lead and Copper Rule 90th-percentile result for lead and copper — the highest reported for City of Frederick. Health standards: EWG's published drinking water standards, updated February 2025. Levels vary by sampling point and date, and being above a health standard is not a legal violation.
10 contaminants above EWG's health guidelines
Everything EWG found above its guideline in Frederick County's water, from testing in 2015-2024. 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 |
|---|---|---|---|
| Haloacetic acids (HAA9) | 41.5 ppb | 0.06 ppb | 692× |
| Haloacetic acids (HAA5) | 38.5 ppb | 0.1 ppb | 385× |
| Total trihalomethanes (TTHMs) | 50.4 ppb | 0.15 ppb | 336× |
| Bromodichloromethane | 4.08 ppb | 0.06 ppb | 68× |
| Chloroform | 13.9 ppb | 0.4 ppb | 35× |
| Bromochloromethane | 0.579 ppb | 0.06 ppb | 9.7× |
| Dibromochloromethane | 0.828 ppb | 0.1 ppb | 8.3× |
| Nitrate and nitrite | 0.695 ppm | 0.14 ppm | 5× |
| Chromium (hexavalent) | 0.0609 ppb | 0.02 ppb | 3× |
| Nitrate | 0.350 ppm | 0.14 ppm | 2.5× |
Source: EWG Tap Water Database, City of Frederick (MD0100015).
The fix for Frederick County water
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Common in U.S. tap water
Frederick County water quality FAQ
Is Frederick County, MD tap water safe to drink?
Public water in Frederick County meets federal EPA legal limits. But "legal" is not the same as "clean": across the Piedmont reservoirs, rivers & wells, independent testing routinely finds contaminants like total trihalomethanes (TTHMs) and haloacetic acids (HAA5) above EWG's stricter health guidelines. Enter your zip code above to see your exact utility's record.
What contaminants are common in Frederick County water?
For the Piedmont reservoirs, rivers & wells, the contaminants that most often exceed health guidelines are total trihalomethanes (TTHMs), haloacetic acids (HAA5), nitrates (agricultural runoff), hexavalent chromium (chromium-6) and PFAS (forever chemicals). Your specific levels depend on your utility, which you can look up by zip code above.
Does Sanavia install reverse osmosis systems in Frederick County?
Yes. Frederick County is roughly 43 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 Frederick County tap water come from?
Frederick County's primary public water system is City of Frederick, which serves roughly 54,000 people. It sits in the Piedmont reservoirs, rivers & wells, 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 Frederick County tested for these contaminants?
No. Private wells are not covered by municipal testing, so the responsibility falls on the homeowner. If your Frederick 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 Piedmont reservoirs, rivers & wells
Each of these is a plain-English guide to a contaminant class common in Frederick County and the surrounding Piedmont reservoirs, rivers & wells — what it is, the health context, and what actually removes it.
Reverse osmosis in Frederick County, MD
City of Frederick treats this water to the federal standard, yet the contaminants listed above still exceed EWG’s stricter health guidelines — Total trihalomethanes (TTHMs), Haloacetic acids (HAA5), 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.
Fit it yourself
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Full testing record for Frederick County · Find a local installer
Detailed city water reports
For the largest DC-metro utilities we publish the full measured contaminant table.
Nearby areas we serve
What's in your Frederick County tap?
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