Is Tredyffrin, PA tap water safe?
Data: U.S. EPA · How we read the data · How we check it
Summary
Aqua Pennsylvania Main System had PFAS above the 2024 federal limits (PFOA, PFOS) in EPA's 2023–2025 testing.
Is it an emergency? No: PFAS limits are about years of exposure, not a glass of water, and nothing in EPA's data calls for you to stop drinking the water today. If your utility issues a boil-water or do-not-drink notice, follow it.
Aqua Pennsylvania Main System supplies Tredyffrin (822,600 people).
Water system
Aqua Pennsylvania Main System
822,600 people · Surface water · EPA ID PA1460073
Buys treated water from Aqua Pennsylvania West Chester, Aqua Pennsylvania Bensalem, Phoenixville Water Dept, Aqua Pennsylvania Uwchlan, BCWSA Main Lower South, Philadelphia Water Department, Chester Water Authority.
| PFAS | Highest average | Limit |
|---|---|---|
| PFOA Above limit | 11.8 ppt | 4 ppt |
| PFOS Above limit | 8.9 ppt | 4 ppt |
| PFHxS Detected, below limit | 7.4 ppt | 10 ppt |
| PFNA Detected, below limit | 8.82 ppt | 10 ppt |
| HFPO-DA (GenX) Not detected | – | 10 ppt |
ppt = parts per trillion. "Highest average" is the highest average at any of the system's entry points, the way EPA compares results with the limits.
For context: the PFOA average is higher than at 95% of the Pennsylvania systems EPA tested and the PFOS average is higher than at 91% of the Pennsylvania systems EPA tested.
Lead: 0 ppb at the 90th percentile (Sep 2025, and 9 in 10 homes sampled were at or below it) Below action level
Health-based violations since 2016: 2
Across Pennsylvania, 85 of 360 water systems EPA tested had PFAS above a 2024 federal limit, and 76 systems were above the lead action level in results from the last five years. Pennsylvania results.
Tredyffrin homes and lead pipes
Lead service lines and lead solder were allowed until 1986, so homes from before then are the ones to check. How to check your own line.
Housing: Census American Community Survey 2020–2024 5-year estimates for Tredyffrin township (tables B25034, B25003). Estimates for small places have a margin of error.
How nearby cities compare
| City | PFAS | Lead (90th pct.) |
|---|---|---|
| Upper Merion 4 mi Aqua Pennsylvania Main System | Above limit | 0 ppb |
| Radnor 5 mi Aqua Pennsylvania Main System | Above limit | 0 ppb |
| Lower Providence 6 mi Aqua Pennsylvania Main System | Above limit | 0 ppb |
| Norristown 7 mi Aqua Pennsylvania Main System | Above limit | 0 ppb |
| Haverford 9 mi Aqua Pennsylvania Main System | Above limit | 0 ppb |
| Lower Merion 9 mi Aqua Pennsylvania Main System | Above limit | 0 ppb |
Tredyffrin ZIP codes (4)
- 19087
- 19301
- 19312
- 19333
Questions
Is Tredyffrin tap water safe to drink?
Aqua Pennsylvania Main System had 2 health-based violations since 2016, and EPA testing found PFAS above the 2024 federal limits, which it must meet by 2029. Utility data can't show lead from your own pipes: if your home was built before 1986, test your tap. Your utility's annual Consumer Confidence Report is the official summary.
Who supplies water in Tredyffrin, PA?
Aqua Pennsylvania Main System, which serves 822,600 people.
Does Tredyffrin tap water have PFAS?
Yes. EPA's 2023–2025 testing found entry-point averages above the 2024 federal limits for PFOA and PFOS at Aqua Pennsylvania Main System. Systems have until 2029 to meet them.
Do Tredyffrin homes have lead pipes?
Census estimates put 59% of Tredyffrin homes as built before 1980 (Pennsylvania: 67%). Lead service lines and lead solder were allowed until 1986, so older homes are more likely to have them. Aqua Pennsylvania Main System's service line inventory says what your line is made of. The only way to know for your home is to check the line where it enters the house and test your tap.
Source: U.S. EPA drinking water records and PFAS testing (UCMR 5). How we read the data.