Local water facts · Maryland
St. Mary's County MetCom (Lexington Park) serves 43,030 people from Groundwater (coastal plain aquifers). The numbers below are from the utility’s own published testing, compiled by the EWG Tap Water Database (June 2026). The water is legal — the question is how it compares to health guidelines, which sit well below the legal limits.
Each card shows how far a contaminant sits above its health guideline — the level scientists consider protective over a lifetime of drinking. A system can pass every legal test and still carry these levels.
4.7 ppb found · health guideline 0.004 ppb · legal limit 10 ppb
Cancer-linked2.42 ppb found · health guideline 0.06 ppb
Cancer-linked Read the research on Haloacetic acids (HAA9) →5.69 ppb found · health guideline 0.15 ppb · legal limit 80 ppb
Cancer-linked Read the research on Total trihalomethanes (TTHMs) →1.08 ppb found · health guideline 0.06 ppb
Cancer-linked Read the research on Bromodichloromethane →1.58 ppb found · health guideline 0.1 ppb · legal limit 60 ppb
Cancer-linked Read the research on Haloacetic acids (HAA5) →0.85 ppb found · health guideline 0.1 ppb
Cancer-linked Read the research on Dibromochloromethane →0.3 pCi/L found · health guideline 0.05 pCi/L · legal limit 5 pCi/L
Cancer-linked1.89 ppb found · health guideline 0.4 ppb
Cancer-linked Read the research on Chloroform →0.145 ppb found · health guideline 0.06 ppb
Cancer · reproductive harmEach bar starts at the health guideline and runs on a log scale — the faint ticks mark 10× and 100× over; the dark notch is the legal limit where one exists.
Health-effect labels and guideline levels above come from the EWG Tap Water Database (June 2026) — advisory benchmarks set by EWG’s researchers (methodology), not legal standards. The utility’s water meets federal legal limits.
Think per glass: at 1,174× the guideline, one glass of tap water carries what 1,174 glasses would hold at the health-guideline level. The top flag here is Arsenic. Not an emergency — but worth knowing, because the fix is specific and usually simpler than people expect.
ZIP codes served by St. Mary's County MetCom (Lexington Park) include 20606, 20609, 20618, 20619, 20620, 20621, 20624, 20626, 20628, 20630, 20634, 20636, 20650, 20653 and 12 more. Type yours on the free report page to see the version for your address.
Want it for your exact address? The free report matches your ZIP to this data, scores it, and shows which fix covers which flag — see your full free report. Reading tips: how to read a water report in 2 minutes.
Every system we track, plotted by Water Score — 0 to 100, higher is safer.
St. Mary's County MetCom (Lexington Park) scores 19/100 — ranking #26 of 58 tracked systems.
No single filter does everything — each option covers different flags, so the right answer depends on what’s in your water and how your house is set up. You’re weighing options, not grades of good.
Good on chlorine taste and some disinfection byproducts. Cartridges fade fast — about every 2 months.
The drinking-water workhorse: handles PFAS, nitrate, arsenic and most of the hard flags — at one tap. How Reverse Osmosis (RO) installation works →
Treats every tap and protects pipes and appliances — usually paired with Reverse Osmosis (RO) for the kitchen. What a softener fixes (and can’t) →
The full breakdown of what each option does and can’t do: the honest 60-second version · all the free guides.
Type your ZIP, get the full picture free: every flag, what it means per glass, and which fix covers it. If you’d rather have a person look at it with you, the free in-home Home Water Checkup tests what no city report can see — your heater, pressure, and hardness.
Get my free water report Book a free Home Water CheckupThey probably haven’t seen these numbers. Send them this page — it takes 10 seconds, and they get their own free report.
📄 Get the printable one-page report (PDF)
Grab the postable Water Score card →