What's in Montgomery County, MD tap water?
Montgomery County sits about 18 miles from our Arlington base and is served primarily by Washington Suburban Sanitary Commission, which provides water to roughly 1,900,000 people. It draws from the Potomac River watershed. Most of the DC metro area drinks treated Potomac River water. Because that surface water is heavily disinfected to stay safe across a long distribution system, the contaminants that most often exceed EWG's stricter health guidelines here are chlorination byproducts, alongside unregulated contaminants like PFAS and hexavalent chromium.
Find a local installerWSSC Water quality report, explained
What testing of WSSC Water shows for Montgomery County, compared with EWG's health guidelines. Being above a guideline is not a legal violation.
Primary water system (EPA)
Washington Suburban Sanitary Commission
Serves about 1,900,000 people
11
over guideline
"× over" compares the detected level to EWG's stricter health guideline, not the federal legal limit.
Measured by the EPA · Montgomery County, MD
Montgomery County, MD tap water is fully legal.
It is also 5.3× the health standard for lead.
Washington Suburban Sanitary Commission runs Montgomery County's water, drawing from surface water and supplying about 1,900,000 people through 438,639 service connections. A system that size runs a long distribution network, and water spends days in it between the plant and the tap.
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
Harm to fetal growth and child development · no federal limit exists
The EPA's latest round found 2 PFAS compounds in this supply. Lead sampling put the ninetieth percentile at 1.05 ppb — meaning nine in ten homes tested below that, and one in ten above it. It has no violations on file.
Washington Suburban Sanitary Commission, on the EPA's record
- Source
- surface water
- Connections served
- 438,639
- People served
- 1,900,000
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 Washington Suburban Sanitary Commission. 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.
The fix for Montgomery County water
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Reverse osmosis under your sink, for the 11 contaminants over EWG guidelines in water from WSSC Water.
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Common in U.S. tap water
Montgomery County water quality FAQ
Is Montgomery County, MD tap water safe to drink?
Public water in Montgomery County meets federal EPA legal limits. But "legal" is not the same as "clean": across the Potomac River watershed, 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 Montgomery County water?
For the Potomac River watershed, the contaminants that most often exceed health guidelines are total trihalomethanes (TTHMs), haloacetic acids (HAA5), hexavalent chromium (chromium-6), PFAS (forever chemicals) and lead (from older service lines). Your specific levels depend on your utility, which you can look up by zip code above.
Does Sanavia install reverse osmosis systems in Montgomery County?
Yes. Montgomery County is roughly 18 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 Montgomery County tap water come from?
Montgomery County's primary public water system is Washington Suburban Sanitary Commission, which serves roughly 1,900,000 people. It sits in the Potomac River watershed, 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 Montgomery County tested for these contaminants?
No. Private wells are not covered by municipal testing, so the responsibility falls on the homeowner. If your Montgomery 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 Potomac River watershed
Each of these is a plain-English guide to a contaminant class common in Montgomery County and the surrounding Potomac River watershed — what it is, the health context, and what actually removes it.
Reverse osmosis in Montgomery County, MD
WSSC Water 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), Hexavalent chromium (chromium-6) 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.
Lead is the one nothing upstream can fix. It does not arrive from the treatment plant; it comes off the service line and the household plumbing in between, which is why two houses on the same street test differently. A reverse osmosis membrane sits at the end of that run, after every pipe the water has already passed through.
Fit it yourself
$999, under the sink, with the included instructions.
We fit it for you
$1,250 installed in Montgomery County.
Full testing record for Montgomery 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 Montgomery County tap?
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