New Jersey tap water / Towns / Mercer County
Trenton, NJ tap water quality
Trenton's PFAS compliance results in 2025 were below both New Jersey and federal limits.
Trenton, in Mercer County, has about 91,506 residents. Virtually all of them live inside the service area of Trenton Water Works, according to New Jersey DEP's service area map.
Correction, November 7, 2026. From October 30 to November 7, 2026, the pages for Trenton Water Works and the towns it serves (Trenton and Ewing) said the system's 2025 report gave no value for PFOA or PFNA, and showed PFOS only. The report does list them: PFOA at 1.33 ppt and PFNA at 0.32 ppt in its Amount Detected column. The pages now show all three. All three values are below New Jersey's and EPA's limits, so the PFAS result for these towns hasn't changed. All corrections.
PFAS in the 2025 report Amount detected, Trenton Water Works
- PFOA1.33 pptNJ limit 14 · Federal limit 4Below both limits
- PFOS0.99 pptNJ limit 13 · Federal limit 4Below both limits
- PFNA0.32 pptNJ limit 13 · Federal limit 10Below both limits
Is Trenton tap water safe?
We don't say whether Trenton's tap water is safe to drink: that's a health question, for your doctor or your utility. What we show is what the utility reported next to New Jersey's and EPA's legal limits, starting with PFAS here; hardness and lead follow below.
For PFAS, the Trenton Water Works' 2025 water quality report lists the amount detected: 1.33 ppt of PFOA, 0.99 ppt of PFOS and 0.32 ppt of PFNA. The report doesn't say whether that figure is a single result or an average. These were below both New Jersey's limits (14 ppt for PFOA, 13 ppt for PFOS and 13 ppt for PFNA) and EPA's national limits (4 ppt for PFOA, 4 ppt for PFOS and 10 ppt for PFNA). The statewide PFAS table puts these figures next to the other water systems on this site.
Hardness and lead in Trenton's water
- Hardness
- 107 mg/L6.3 grains per gallon, moderately hardThe utility's report lists one value for hardness, 107 mg/L (2025).New Jersey's recommended upper limit 250 mg/L (for taste and appearance; not enforceable); no federal limit.
- Lead, 90th percentile of home taps
- 4.40 ppbHigher of two 2025 sampling rounds: 4.40 ppb in round 2, 3.27 ppb in round 1.Action level: 15 ppb, dropping to 10 ppb in November 2027
6.3 grains per gallon in Trenton's report: size a water softener for Trenton. See how hard the water is elsewhere in New Jersey.
Filtering Trenton's tap water at home
The utility's PFAS compliance results were below the federal limits. If you still want a filter, or you're concerned about lead from your home's pipes, look for one certified to NSF/ANSI Standard 53 for the contaminant you care about.
Where does Trenton's water come from?
The Trenton Water Works' 2025 report lists its own sources as Delaware River.
Local factors in Trenton
Trenton's municipal boundary on aerial photos taken between April 29, 2022 and August 20, 2023. The town boundary and the water system's service area aren't always the same.
Source: USDA National Agriculture Imagery Program, via USGS The National Map; boundary from NJ Office of GIS.
Age of homes
79% (margin of error ±4 percentage points) of homes in Trenton were built before 1980 (Mercer County: 64%, New Jersey: 63%; U.S. Census ACS 2020-2024). The utility's water quality report describes water leaving the system, not the plumbing inside a home; why the build year matters for lead.
Source: U.S. Census Bureau, American Community Survey 2020-2024 5-year estimates, table B25034 (Year Structure Built).
Radon
NJDEP places Trenton in Radon Tier 2 (moderate potential: 5 to 24 percent of tested homes at or above 4 picocuries per liter) based on indoor radon tests (2015). In that report, 11% of the 6,260 homes tested in Trenton were at or above 4 picocuries per liter. NJDEP recommends testing every home regardless of tier. How radon tiers work.
Source: New Jersey DEP Radon Section, 2015 Radon Tier Assignment Report; the same figures appear in NJDEP's current municipal tier list.
Known contaminated sites
NJDEP lists 164 sites in Trenton where soil or groundwater contamination has been confirmed (October 14, 2026). These are places under cleanup oversight; they do not mean that tap water from the public system is contaminated. The public water system is tested and treated separately.
Source: New Jersey DEP, Known Contaminated Sites List map layer, retrieved October 16, 2026, with site-by-site lists in NJDEP's Known Contaminated Sites reports.
Water and sewer bills
In the Census Bureau's survey (ACS 2020-2024, about this question), 56% (margin of error ±3 percentage points) of occupied homes in Trenton pay a separate charge for water and sewer; the rest report no charge or a charge included in other fees, such as rent. Among the homes that pay, 26% (margin of error ±3 percentage points) report $1,000 or more for the year (25% in Mercer County, 30% statewide), as households report it rather than as the utility bills it.
Source: U.S. Census Bureau, American Community Survey 2020-2024 5-year estimates, table B25134 (Annual Water and Sewer Costs).
ZIP codes covering Trenton: 08608, 08609 (shared with Hamilton Township), 08611 (shared with Hamilton Township), 08618 (shared with Ewing), 08629 (shared with Hamilton Township), 08638 (shared with Ewing). Source: U.S. Census Bureau 2020 ZIP Code Tabulation Areas.
Sources. 2025 water quality report, Trenton Water Works (public water system NJ1111001), checked against the original in October and November 2026; EPA Safe Drinking Water Information System. How we check the data · report an error.
Other towns on the same water system
These towns get their water from the Trenton Water Works, so their results match Trenton's:
Mercer County towns on other water systems
| Town | Water system | PFAS result |
|---|---|---|
| Princeton tap water | NJ American Water, Raritan system | above federal PFAS limit |
| West Windsor tap water | NJ American Water, Raritan system | above federal PFAS limit |