waterbycounty
EPA SDWIS

Middlesex County Water Quality

Middlesex County, New Jersey

Water Grade

C

Water Score

61.7

Violations

35

State Rank

#9

of 21 (1 = best)

EPA SDWIS Compliance

Drinking Water Quality

Water Quality Grade

C

Based on EPA compliance history and violation data

Water Score

61.7/100

Higher = better quality

Health Violations

35

Health-based violations

Violation Rate

5.3%

Systems with violations

Water Advisory: Middlesex County

Water Verdict

Middlesex County receives a fair water quality assessment with a grade of C and a score of 61.7 out of 100. The water supply meets baseline federal standards, but there may be periods of elevated contaminant levels or infrastructure concerns worth monitoring.

Violation Context

Middlesex County has recorded 35 health-based violations, indicating multiple instances where federal contaminant limits or treatment requirements were not met. At 5.3 violations per 1,000 residents, this rate is moderate and suggests recurring water quality challenges.

Consumer Guidance

Tap water in Middlesex County meets baseline standards, but residents who are immunocompromised or have young children may want to use an NSF-certified water filter as a precaution. With 35 recorded health violations, staying informed about utility communications and boil-water notices is especially important. For long-term peace of mind, request your utility's latest Consumer Confidence Report and consider independent water testing if you have specific health concerns.

Regional Context

Middlesex County has better water quality than the average county in New Jersey. Its water score is 6 points higher than the state average, indicating stronger water system performance relative to neighboring counties.

Past 5 years

Water Quality Monitoring

Monitoring Sites

258

Active in the past 5 years

Measurements Recorded

37K

36,640 total readings

Most Measured

  • Physical
  • PFAS,Perfluorinated Alkyl Substance
  • Microbiological

Categories measured most frequently

Data from the EPA Water Quality Portal (WQP), aggregating monitoring records from federal, state, and tribal sources. Each measurement represents a single sample analyzed for a specific characteristic (e.g., E. coli, pH, dissolved oxygen, nitrogen).

Live USGS Streamgage

River & Stream Conditions

Current Discharge

15.7cfs

May 14, 6:30 PM UTC

vs Long-Term Average

28%

Well below typical

Primary Streamgage

Lawrence Brook at Westons Mills NJ

USGS site
01405030
Drainage area
44.9 sq mi
Long-term mean
56.1 cfs

One representative streamgage (the one with the largest drainage area in the county). Many counties have multiple gauges — this view summarizes the primary one. The long-term mean is the full-record annual average; "% of typical" compares the latest reading against that average.

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Frequently Asked Questions

What is the water quality in Middlesex County, New Jersey?
Middlesex County, New Jersey has a drinking-water quality grade of C with a score of 61.7/100, based on EPA SDWIS compliance data. The county has 35 health-based drinking water violations over the past 5 years. Watershed health, monitoring records, and live streamflow are reported separately on this page.
Are there any water violations in Middlesex County?
Middlesex County has 35 health-based drinking water violations recorded by the EPA over the past 5 years. Health-based violations indicate instances where contaminant levels exceeded EPA Maximum Contaminant Levels (MCLs). Violations may have been resolved — check with your local water utility for current status.
How much water-quality monitoring happens in Middlesex County?
EPA's Water Quality Portal records 36,640 measurements from 258 monitoring sites in Middlesex County over the past five years. The most frequently measured characteristic groups are Physical, PFAS,Perfluorinated Alkyl Substance, Microbiological. Each measurement is a single sample analyzed for one characteristic (E. coli, pH, dissolved oxygen, etc.). High monitoring density means more scientific evidence behind any reported signal — it does not by itself indicate water quality.
What's happening with rivers in Middlesex County right now?
Middlesex County's primary USGS streamgage on the Lawrence Brook is currently reading 15.7 cubic feet per second — 28% of the long-term mean of 56.11 cfs. This is well below typical — often a signal of drought stress on source water. For genuine real-time data, visit waterdata.usgs.gov.
How does Middlesex County water compare to the New Jersey average?
Middlesex County's SDWIS water quality score of 61.7/100 is higher than the New Jersey state average of 55.7. The average water quality grade across New Jersey is D, based on data from 21 counties with available SDWIS data.
Is tap water safe to drink in Middlesex County?
Based on EPA SDWIS data, Middlesex County has a water quality grade of C (61.7/100). This indicates moderate compliance. Some violations have been recorded but overall standards are maintained. The grade speaks to the public water system, not the watershed — for watershed-level concerns, see the Watershed Health zone. For the most up-to-date information, contact your local water utility or review your Consumer Confidence Report (CCR).
Why does Middlesex County have so many water violations?
Middlesex County has 35 health-based drinking water violations on record from the EPA SDWIS database. A higher violation count can result from aging infrastructure, underfunded water utilities, agricultural runoff contamination, or industrial pollution. Counties with more water systems may also see more violations simply due to scale. Residents concerned about water quality should consider independent water testing and home filtration systems.
How does Middlesex County rank for water quality in New Jersey?
Middlesex County ranks #9 out of 21 counties in New Jersey by SDWIS water quality score (1 = best). With a score of 61.7/100, it falls in the middle third of counties statewide. The ranking reflects EPA SDWIS compliance only — not watershed impairment, monitoring density, or streamflow, which are tracked separately on this page.

Counties with Similar Water Quality

Mercer County

New Jersey

B

62.3

Water score

Burlington County

New Jersey

C

60.6

Water score

Ocean County

New Jersey

B

63.0

Water score

Data Sources

Drinking-water compliance data from the EPA Safe Drinking Water Information System (SDWIS) via the ECHO enforcement database. Scores reflect compliance history and health-based violation counts.

Water-quality monitoring counts from the EPA Water Quality Portal (WQP) — federated USGS, EPA, and state agency sampling records over a rolling 5-year window.

Live streamflow from the USGS National Water Information System (NWIS) — continuous discharge measurements from the largest-drainage gauge in each county, compared against the full-record long-term annual mean.

Disclaimer: This data is informational only. It is not health, legal, or professional advice. For concerns about your specific water supply, contact your local water utility.

By Logan Johnson, Founder & Data EditorUpdated Reviewed by Logan Johnson, Founder & Data Editor

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