01The verdict: is Williamstown water safe?
Williamstown's drinking water has significant quality concerns based on EPA testing data. With a grade of C- (56.6/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 1 water system serves approximately 2,390 residents using surface water (rivers, lakes, or reservoirs).
Lead is over its legal limit
Measured at 32.0 ppb against the EPA Action Level of 15 ppb. The ledger below shows how far over — and which filter removes it.
See the measurement ↓2K people, 1 system
All figures on this page come from federal EPA compliance and testing data for the systems serving this city.
See the systems ↓14 violations in the last five years
Recent compliance history is the best predictor of future problems — the year-by-year record is below.
See the record ↓Williamstown's drinking water received a grade of C- (56.6 out of 100), indicating poor water quality. The city's 1 water system serves approximately 2,390 residents using surface water.
Lead levels were measured at 32.0 ppb (90th percentile), which exceeds the EPA action level of 15 ppb. This system has not yet been tested for PFAS under the EPA UCMR 5 program. The system has 123 violations on record, including 0 health-based violations. 8 remain unresolved.
Williamstown ranks #284 out of 559 cities in Pennsylvania for water quality, placing it below average in the state. The city draws from surface water sources, which are more susceptible to seasonal runoff and agricultural contamination, requiring extensive multi-barrier treatment including coagulation, filtration, and disinfection. Lead levels exceed the EPA action level of 15 ppb, which typically indicates aging lead service lines or lead solder in the distribution system. An NSF 53-certified filter is strongly recommended for drinking and cooking water. As a small community water system, Williamstown may have fewer resources for advanced treatment technologies and infrastructure upgrades compared to larger utilities. The system has seen 14 violations in the past five years, suggesting a pattern of compliance challenges that residents should monitor closely.
02What's in Williamstown's water
Every contaminant flagged in Williamstown, on one shared scale: distance to its own legal limit. The red line is the limit — anything past it is out of compliance, and the closer a bar gets, the less headroom the system has.
Over Limit — EPA Action Level: 15 ppb
Exceeds the EPA action level. Lead enters at the service line, not the treatment plant — your address matters more than the city average. Lead service line replacement and an NSF 53-certified point-of-use filter are recommended.Full contaminants report
| Contaminant | Detected Level | EPA Limit | Unit | Category | Status |
|---|---|---|---|---|---|
| Lead (90th percentile) LeadHeavy Metal A toxic heavy metal that can leach into drinking water from older pipes, solder, and fixtures. No amount of lead in water is considered safe. Health EffectsBrain and nervous system damage in children, kidney damage, high blood pressure, and reproductive problems in adults. EPA Limit15 ppb action level Common SourcesCorrosion of lead pipes, lead solder, brass faucets, and household plumbing. | 32.0 | 15 | ppb | Inorganic | Over Limit |
Cities ranked by 90th-percentile lead PF PFAS in Pennsylvania
Cities ranked by compounds detected Cu Copper in Pennsylvania
Cities ranked by 90th-percentile copper
03Williamstown's ten-year track record
Each box is one year. A green check means no EPA violations; a numbered badge counts that year's violations — red if any were health-based, amber if they were monitoring or paperwork issues. The system has 123 violations on record, including 0 health-based violations. 8 remain unresolved.
4 of the last ten years were clean. The numbered years had EPA violations — red when any were health-based, amber when they were paperwork or missed-testing issues.
▲ Up 26 ppb since 1993. The latest reading (32 ppb, 2007) is over the action level. Sampled at higher-risk homes (90th percentile).
04Where Williamstown's water comes from
Williamstown's drinking water comes primarily from surface water sources such as rivers, lakes, or reservoirs.
Surface Water
Rivers, lakes, or reservoirs — more exposed to runoff, agriculture, and seasonal swings than groundwater.
Local treatment
Multi-barrier treatment: coagulation, sedimentation, filtration, and disinfection to meet EPA standards.
1 system
1 water system, operated under local government ownership.
2,390 people
Residents served across Williamstown's service area.
Surface water systems require multi-stage treatment including coagulation, sedimentation, filtration, and disinfection to meet EPA Safe Drinking Water Act standards. These sources can be impacted by seasonal changes, stormwater runoff, upstream agriculture, and industrial discharge. The system is operated by local government ownership and serves approximately 2,390 people through 1 water system.
| System name | PWSID | Population | Source |
|---|---|---|---|
| WILLIAMSTOWN BORO AUTH | PA7220037 | 2,390 | Surface Water |
Water bodies near Williamstown
As a surface-water system, these water bodies may directly influence Williamstown's drinking water supply.
05Pressure on Williamstown's watershed
Outside forces that shape what reaches the treatment plant. None of these is a verdict on the tap by itself — but each adds pressure worth knowing about.
Industrial discharge
3 facilities within 10 miles reported 33k lb released to surface water in the latest EPA Toxics Release Inventory. Proximity doesn't equal tap contamination — treatment and hydrology decide — but it's pressure on the watershed.
Flood & storm history
10 federal disaster declarations on record for Dauphin County. Flooding and severe storms can overwhelm treatment plants, cause sewage overflows, and push runoff into supplies.
Drought
Dauphin County is in D1 (moderate drought) per the U.S. Drought Monitor (week of Jul 2026). Drought can raise disinfection-byproduct levels and taste/odor issues as utilities draw from lower reservoirs.
06How Williamstown compares
Scores for nearby Pennsylvania cities on one line, with the average marked.
dashed line = Pennsylvania average (49/100)
Williamstown scores 56.6/100 — above the Pennsylvania average of 49/100. It outscores 8 of 10 nearby cities. Full Pennsylvania rankings →
79.8 / 100FBryn Mawr, PA
34.2 / 100FPittsburgh, PA
44 / 100AMcmurray, PA
86.8 / 100DGreensburg, PA
46.7 / 100FHarrisburg, PA
35.6 / 100
Compare all cities in the county — grades, violations, and contaminant data side by side.→
07What to do at home
Steps matched to what testing actually found in Williamstown's water — not generic advice.
Filter drinking & cooking water
NSF 53-certified pitcher or under-sink filter. Lead level (32.0 ppb) exceeds the EPA action level of 15 ppb
Compare tested filters →Flush taps & check your service line
Lead leaches from pipes as water sits. Run cold water 30 seconds before drinking (especially mornings), and ask the utility whether your address still has a lead service line.
Lead risks explained →Watch for Williamstown alerts
This area has a history of flood declarations — after severe weather, watch for boil-water advisories from the utility, and check the live alerts on this page.
All water alerts →Frequently asked questions
Is Williamstown, PA tap water safe to drink?
Williamstown's water quality earned a grade of C- (56.6/100). Significant issues have been found. A water filter is strongly recommended. The city ranks #284 out of 559 cities tested in Pennsylvania.
What contaminants are in Williamstown's water?
Lead was measured at 32.0 ppb (90th percentile). 123 violations are on record.
How is Williamstown's water quality grade calculated?
The grade is based on four factors: violation history (40%), lead and copper levels (25%), PFAS contamination (25%), and regulatory compliance (10%). The score is also adjusted based on how complete the available data is. See our methodology page for full details.
Do I need a water filter in Williamstown?
Yes — lead levels exceed the EPA action level of 15 ppb. We recommend an NSF 53-certified filter or reverse osmosis system. Based on current data, basic filtration should suffice for additional peace of mind.
Where does Williamstown's water come from?
Williamstown's water is sourced from Surface water. The city has 1 water system serving approximately 2,390 residents.
How does Williamstown's water compare to other cities?
Williamstown ranks #284 out of 559 cities in Pennsylvania (better than 49% of state cities) and #12223 out of 15382 cities nationally (21th percentile). The grade of C- reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.
Does Williamstown's small water system affect quality?
Williamstown's system serves approximately 2,390 residents. Small community water systems (under 3,300 people) may have fewer financial resources for infrastructure upgrades and advanced treatment technologies. However, they are held to the same EPA drinking water standards as larger systems. This system has 123 violations on record.