Summer offer: $250 off the Hydra system. Shop now →
Local water report

What's in Potomac, MD tap water?

Potomac is served by WSSC Water from the river it shares a name with. The supply meets every federal limit, and still carries haloacetic acids and trihalomethanes at multiples of EWG's health-based guidelines — the gap between legal and safe that a reverse-osmosis system exists to close.

Served by
WSSC Water
Potomac River + Patuxent River
4
over guideline
Detected 49 ppb avg · EWG guideline 0.1 ppbCancer
Detected 66 ppb avg · EWG guideline 0.15 ppbCancer; fetal development
Detected 0.13 ppb avg · EWG guideline 0.02 ppbCancer (stomach)
Arsenic10× over
Detected detected · EWG guideline 0.004 ppbCancer; cardiovascular; developmental
Source: WSSC Water data via EWG ↗

Zip codes covered: 20854, 20859 and surrounding Potomacareas. “× over” compares the detected level to EWG's health guideline, not the federal legal limit.

PFAS detected · EPA UCMR5 (2023-2025)

2 PFAS “forever chemicals” found in Potomac, MD's water

The EPA's most recent national testing round detected PFAS in Washington Suburban Sanitary Commission's supply. The EPA's 2024 legal limit for PFOA and PFOS is just 4 ppt, and its own health goal is zero, no level is considered safe.

PFAS compoundDetected (ppt)
PFPeA6.7
PFHxA4.8

Reverse osmosis is independently rated the most effective way to remove PFAS at the tap.

See the fix

Source: EPA Fifth Unregulated Contaminant Monitoring Rule (UCMR5), highest detected result per compound for Washington Suburban Sanitary Commission. Levels vary by sampling point and date. Learn more about PFAS.

How to get Potomac water off that list

Here is the good news: everything above comes out at your kitchen tap. WSSC Water treats the water for the whole Potomac system, but a reverse osmosis system finishes the job at your sink, catching what city treatment leaves behind. The Sanavia Hydra fits under a standard Potomac sink and is NSF-certified to cut haloacetic acids (haa5) and the rest by up to 99%.

Potomac water quality FAQ

Is Potomac, MD tap water safe to drink?

WSSC Water water meets all federal EPA legal limits. However, independent EWG testing finds 4 contaminants above its stricter health-based guidelines, including Haloacetic acids (HAA5) and Total trihalomethanes (TTHMs). Legal compliance and health-optimal water are not the same thing.

What contaminants are in Potomac water?

The most notable contaminants above EWG health guidelines are Haloacetic acids (HAA5), Total trihalomethanes (TTHMs), Chromium-6 (hexavalent), Arsenic. These are largely disinfection byproducts and trace metals common to the region's water sources.

Does a reverse osmosis system remove these contaminants?

Yes. A reverse osmosis system like the Sanavia Hydra uses a 0.0001-micron membrane plus multi-stage carbon filtration, NSF-certified to reduce every contaminant class detected in Potomac water, at your tap, regardless of what the utility does upstream.

Understand what's in the water

The contaminants flagged in Potomac water

Plain-English guides to what WSSC Watertesting turns up above EWG's health guidelines — what each one is, and what actually removes it.

See all contaminant guides →