WSSC Water: what's in the water
16 contaminants and water quality measures were reported as detected in the 2025 Water Quality Report, covering 2025.
Where this comes from: Every number below is copied from the published Consumer Confidence Report for WSSC Water, hosted by the Maryland Department of the Environment. Some substances aren't tested every year, so the sample date is shown for each result. Values and limits appear as printed.
Is this your water? WSSC Water serves most of Montgomery and Prince George's counties. Some cities (for example parts of Rockville and Bowie) and some rural areas have their own systems or private wells. Your water comes from the Patuxent or Potomac plant depending on where you live. Check your water bill to confirm your provider.
Everything WSSC Water reported
Tap any contaminant to see what it can do to your body and your home & appliances, the exact values from the report, and which systems can help reduce it.
LeadMetals<2.0 µg/L (ppb)15 µg/LAction level2023
Your body
EPA has set a health goal of zero for lead because no safe level of exposure is known. In children, low-level lead exposure has been linked to lower IQ, learning and attention problems; in adults, to raised blood pressure and kidney effects. Pregnant women and young children are most at risk.
Your home & appliances
Lead itself does not damage plumbing, but its presence is a sign of corrosion: water chemistry that dissolves metal from pipes, solder, and fixtures.
What it is
A metal that usually gets into tap water from lead service lines, lead solder, and older brass fixtures inside buildings, not from the water source itself. Homes built before 1986 are more likely to have lead plumbing.
Exactly as reported
- Lead: <2.0 µg/L (ppb) (90th percentile) · range ND–8.11 · Action level 15 · health goal 0 · violation: No · sampled 2023Note: The report notes the lead action level will be lowered to 10 µg/L beginning November 1, 2027.
PFASIndustrial & farm chemicals · 9 resultsPatuxent 1.8 · Potomac 3.7 ng/L (ppt) +8 more4.0 ng/LMCL2025
Your body
Exposure to certain PFAS, such as PFOA and PFOS, has been linked to effects including changes in cholesterol, reduced vaccine response in children, lower birth weight, and increased risk of some cancers (EPA; Fenton et al., 2021). In 2024, EPA set drinking water limits for several PFAS.
Your home & appliances
PFAS do not affect plumbing or appliances.
What it is
Per- and polyfluoroalkyl substances are a large family of man-made chemicals used since the 1940s in non-stick, stain- and water-resistant products and firefighting foams. They break down very slowly in the environment and the body.
Exactly as reported
- PFOA: Patuxent 1.8 · Potomac 3.7 ng/L (ppt) (highest level found by plant) · range <1.6–3.7 · MCL 4.0 · health goal 0 · violation: N/A · sampled 2025Note: The report notes PFAS MCL compliance is calculated quarterly and is scheduled to take effect beginning April 26, 2029.
- PFOS: Patuxent 1.8 · Potomac 4.2 ng/L (ppt) (highest level found by plant) · range ND–4.2 · MCL 4.0 · health goal 0 · violation: N/A · sampled 2025Note: The report notes PFAS MCL compliance is calculated quarterly and is scheduled to take effect beginning April 26, 2029.
- PFHxS: Patuxent 1.6 · Potomac 1.9 ng/L (ppt) (highest level found by plant) · range ND–1.9 · MCL 10 · health goal 10 · violation: N/A · sampled 2025
- PFNA: Patuxent ND · Potomac 1.7 ng/L (ppt) (highest level found by plant) · range ND–1.7 · MCL 10 · health goal 10 · violation: N/A · sampled 2025
- PFBS: Patuxent 2 · Potomac 3.0 ng/L (ppt) (highest level found by plant) · range <1.6–3.0 · violation: N/A · sampled 2025
- PFBA (unregulated): Patuxent 2.5 · Potomac 3.3 ng/L (ppt) (average by plant) · range <1.7–4.2 · sampled 2025
- PFHxA (unregulated): Patuxent 1.9 · Potomac 3.7 ng/L (ppt) (average by plant) · range 1.7–4.6 · sampled 2025
- PFPeA (unregulated): Patuxent 2.3 · Potomac 3.8 ng/L (ppt) (average by plant) · range 2.0–4.3 · sampled 2025
- PFHpA (unregulated): Patuxent 0.6 · Potomac 1.0 ng/L (ppt) (average by plant) · range ND–2.1 · sampled 2025
NitrateNutrientsPatuxent 1.4 · Potomac 1.6 mg/L10 mg/LMCL2025
Your body
According to EPA, infants under six months who drink water with nitrate above the federal limit could become seriously ill (blue baby syndrome). Research has also examined links between long-term exposure and other health effects.
Your home & appliances
Nitrate does not harm plumbing. It can indicate that surface water or septic waste is reaching a well.
What it is
A form of nitrogen from fertilizer, manure, and septic systems that can soak into groundwater. It is a common concern in farming areas, including much of the Eastern Shore.
Exactly as reported
- Nitrate: Patuxent 1.4 · Potomac 1.6 mg/L (highest level found by plant) · range 0.4–1.6 · MCL 10 · health goal 10 · violation: No · sampled 2025
Total TrihalomethanesDisinfection byproducts66 µg/L (ppb)80 µg/LMCL2025
Your body
According to EPA, long-term exposure above the federal limit has been linked to liver, kidney, or central nervous system problems and an increased risk of cancer. Studies have associated long-term exposure to chlorination byproducts with bladder cancer.
Your home & appliances
Trihalomethanes do not affect plumbing. They can also be inhaled during hot showers.
What it is
A group of four chemicals (chloroform, bromodichloromethane, dibromochloromethane, bromoform) that form when chlorine reacts with natural organic matter in water. Levels are usually higher at the far ends of a distribution system and in warm months.
Exactly as reported
- Total Trihalomethanes (TTHMs): 66 µg/L (ppb) (highest locational running annual average) · range 14–102 · MCL 80 · health goal N/A · violation: No · sampled 2025
Haloacetic AcidsDisinfection byproducts48 µg/L (ppb)60 µg/LMCL2025
Your body
According to EPA, long-term exposure above the federal limit has been linked to an increased risk of cancer.
Your home & appliances
Haloacetic acids do not affect plumbing.
What it is
Five related chemicals that form when chlorine reacts with natural organic matter in water. Like TTHM, they are tracked at points around the distribution system.
Exactly as reported
- Haloacetic Acids (HAA5): 48 µg/L (ppb) (highest locational running annual average) · range 16–79 · MCL 60 · health goal N/A · violation: No · sampled 2025
RadiumRadiologicalPatuxent 0.2 · Potomac 0.5 pCi/L5 pCi/LMCL2025
Your body
According to EPA, long-term exposure above the federal limit has been linked to an increased risk of cancer.
Your home & appliances
Radium does not affect plumbing, but it can build up in softener resin and filter media.
What it is
A naturally occurring radioactive element in some rock and soil, found in certain Maryland aquifers. Reports list radium-226, radium-228, or the two combined.
Exactly as reported
- Radium 228: Patuxent 0.2 · Potomac 0.5 pCi/L (highest level found by plant) · range 0.1–0.5 · MCL 5 · health goal 0 · violation: No · sampled 2025
Gross alpha activityRadiologicalPatuxent ND · Potomac 3.2 pCi/L15 pCi/LMCL2025
Your body
According to EPA, long-term exposure above the federal limit has been linked to an increased risk of cancer.
Your home & appliances
Alpha emitters do not affect plumbing.
What it is
A screening measurement of total alpha radiation in water, mostly from natural uranium, radium, and related elements in rock.
Exactly as reported
- Gross Alpha: Patuxent ND · Potomac 3.2 pCi/L (highest level found by plant) · range ND–3.2 · MCL 15 · health goal 0 · violation: No · sampled 2025
Beta/photon emittersRadiologicalPatuxent 4.4 · Potomac 6.1 pCi/L50 pCi/LMCL2025
Your body
According to EPA, long-term exposure above the federal limit has been linked to an increased risk of cancer.
Your home & appliances
Beta emitters do not affect plumbing.
What it is
A screening measurement of beta radiation in water, from natural minerals (like potassium-40) and some human-made sources. Water systems compare results to a 50 pCi/L screening level.
Exactly as reported
- Gross Beta: Patuxent 4.4 · Potomac 6.1 pCi/L (highest level found by plant) · range ND–6.1 · MCL 50 · health goal 0 · violation: No · sampled 2025
Coliform bacteria & E. coliMicrobes0.5% % of monthly samples5%MCL2025
Your body
According to EPA, germs indicated by E. coli can cause stomach cramps, diarrhea, nausea, and headaches, and may pose a special risk for infants, young children, and people with severely compromised immune systems.
Your home & appliances
Bacteria do not damage plumbing, but in wells they can point to a cracked well cap, a damaged casing, or nearby septic issues.
What it is
Coliforms are bacteria that are common in the environment. Water systems test for them as an indicator: their presence means germs may be able to get into the water. E. coli is a specific type that indicates fecal contamination.
Exactly as reported
- Total Coliform: 0.5% % of monthly samples (highest % positive per month) · range 0–0.5% · MCL 5% · health goal 0 · violation: No · sampled 2025
CopperMetals0.12 mg/L1.3 mg/LAction level2023
Your body
According to EPA, short-term exposure above the action level has been linked to stomach and intestinal upset. Long-term exposure has been linked to liver or kidney damage, and people with Wilson’s disease are more sensitive.
Your home & appliances
Copper in water points to pipe corrosion, which can lead to pinhole leaks over time. It also leaves blue-green stains on sinks, tubs, and fixtures.
What it is
A metal that mostly enters tap water from corrosion of copper pipes and brass fixtures, especially when water is acidic (low pH) or sits in pipes for hours.
Exactly as reported
- Copper: 0.12 mg/L (90th percentile) · range 0.014–0.23 · Action level 1.3 · health goal 1.3 · violation: No · sampled 2023
FluorideMineralsPatuxent 0.95 · Potomac 0.8 mg/L4 mg/LMCL2025
Your body
EPA sets an enforceable limit of 4.0 mg/L and a secondary standard of 2.0 mg/L. According to EPA, long-term exposure above 4.0 mg/L has been linked to bone disease, and children exposed above 2.0 mg/L may develop dental fluorosis (tooth discoloration or pitting). A 2024 federal NTP review examined fluoride exposure above 1.5 mg/L and children’s IQ.
Your home & appliances
Fluoride does not affect plumbing.
What it is
A mineral that occurs naturally in some groundwater and that many public water systems add at low levels to help prevent tooth decay.
Exactly as reported
- Fluoride: Patuxent 0.95 · Potomac 0.8 mg/L (highest level found by plant) · range 0.5–0.95 · MCL 4 · health goal 4 · violation: No · sampled 2025
ChlorineDisinfectants1.05 mg/L4 mg/LMax. disinfectant2025
Your body
According to EPA, people drinking water containing chlorine well in excess of the federal limit could experience eye or nose irritation or stomach discomfort. Disinfection itself is an important public health protection.
Your home & appliances
Chlorine causes the “pool” taste and smell many people notice. Over time it can dry out rubber seals and gaskets in fixtures and appliances.
What it is
Public water systems are required to disinfect water to control germs, and most use chlorine or chloramine. A small amount stays in the water all the way to your tap.
Exactly as reported
- Free Residual Chlorine: 1.05 mg/L (highest running annual average) · range 0.02–2.11 · Max. disinfectant 4 · health goal 4 · violation: No · sampled 2025
BariumMetalsPatuxent 0.04 · Potomac 0.05 mg/L2 mg/LMCL2025
Your body
According to EPA, long-term exposure above the federal limit has been linked to increased blood pressure.
Your home & appliances
Barium can add to the mineral scale that builds up in water heaters and pipes.
What it is
A naturally occurring metal found in many rock formations, plus discharges from drilling and metal refining.
Exactly as reported
- Barium: Patuxent 0.04 · Potomac 0.05 mg/L (highest level found by plant) · range 0.02–0.05 · MCL 2 · health goal 2 · violation: No · sampled 2025
TurbidityWater qualityPatuxent 0.05 · Potomac 0.06 NTUTT <1 NTUMCL2025
Your body
Turbidity itself has no health effects, but according to EPA, it can interfere with disinfection and give germs a place to grow.
Your home & appliances
Sediment that causes cloudy water can clog faucet aerators, valves, and appliance inlets.
What it is
Turbidity measures how cloudy water is, from suspended particles like silt and clay. Water systems monitor it to show how well their filtration works.
Exactly as reported
- Turbidity (monthly average): Patuxent 0.05 · Potomac 0.06 NTU (highest monthly average by plant) · range 0.02–0.36 · MCL TT <1 NTU · violation: No · sampled 2025
TritiumRadiologicalPatuxent 213.6 · Potomac 124.3 pCi/L20,000 pCi/LMCL2025
Your body
Tritium is regulated under EPA’s beta/photon limit; EPA uses 20,000 pCi/L as the level that corresponds to that limit.
Your home & appliances
Tritium does not affect plumbing.
What it is
A radioactive form of hydrogen made naturally in the atmosphere and by some human activities. It becomes part of water molecules.
Exactly as reported
- Tritium: Patuxent 213.6 · Potomac 124.3 pCi/L (highest level found by plant) · range ND–213.6 · MCL 20,000 · violation: No · sampled 2025Note: The report notes that 20,000 pCi/L corresponds to the 4 mrem/year MCL for beta particle/photon radioactivity.
SodiumMineralsPatuxent 16 · Potomac 22 mg/LNo federal limit2025
Your body
Sodium in water is a small part of most people’s daily intake. People on sodium-restricted diets may want to talk to their doctor; EPA guidance mentions 20 mg/L for people on very low-sodium diets.
Your home & appliances
Sodium itself does not usually affect plumbing.
What it is
A naturally occurring element in groundwater. It also comes from road salt, some water treatment chemicals, and water softeners.
Exactly as reported
- Sodium (unregulated): Patuxent 16 · Potomac 22 mg/L (average by plant) · range 11–34 · sampled 2025
Source: WSSC Water, 2025 Water Quality Report (published 2026, covering 2025), via the Maryland Department of the Environment. Values appear as printed. Detected doesn't mean unsafe; most results are below federal limits.
The information on this site is for general education only and is not medical advice. Talk with a qualified health professional about health concerns. Water treatment equipment performance depends on the system, its certification, and proper maintenance. Data transcribed 2026-10-24. If you spot a difference from the published report, the published report is correct. Please let us know.
Your tap may differ from the system average.
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