waterbycounty
Compiled federal source snapshot

New Jersey Water Quality

Drinking water data for all 21 counties.

Avg SDWIS Compliance Index

59.2

Most Common Five-Year SDWIS Compliance Band

B

Counties with Data

21

of 21 total

County water atlas

New Jersey water signals by county

A state-level 2.5D view across drinking-water compliance, watershed impairment, monitoring density, and streamflow snapshot context. Pin any county, switch layers, then use the lens controls to compare index ranges, recorded violation rates, or impaired watersheds without leaving the page.

Counties

21

Avg SDWIS index

59.2

Watersheds

14

ATTAINS counties

Monitoring

21

19 fresh USGS snapshots

State atlas layers combine EPA SDWIS health-based violations, EPA ATTAINS 303(d) impairment assessments, EPA Water Quality Portal monitoring sites, and representative USGS NWIS streamflow gauges. Streamflow values appear only for fresh pipeline snapshots, not as a continuously updated stream. County pages include the observation time and year.

Prepared by ByCounty Editorial TeamPublished by WaterByCounty

Multi-source coverage in New Jersey

Beyond Drinking Water

EPA SDWIS

21/ 21

counties with drinking-water compliance data

270 health violations statewide (5yr)

EPA ATTAINS

94.1%

avg impaired across 14 counties

97 of 105 assessed bodies impaired

EPA WQP

4,981

monitoring sites across 21 counties

748,015 total readings (5yr window)

USGS NWIS

19

counties with a fresh pipeline snapshot

7 above11 below

State atlas notes

What stands out in New Jersey

County water quality is not one number. The strongest read comes from comparing drinking-water compliance against watershed impairment, monitoring density, and streamflow context. Use these signals as a starting point, then open any county profile for source-level detail.

Compliance spread

Somerset County has the highest value in the published state SDWIS Compliance Index table at 86.2/100, while Salem County has the lowest at 19.6/100. That is a 66.6 point gap inside one state.

Zero health violations

2

3+ health violations

17

Watershed pressure

The atlas impairment layer points to counties where assessed water bodies are most likely to miss state quality standards. Assessment density varies, so compare the percentage with the number of assessed bodies on the county page.

Gloucester County100.0%Hunterdon County100.0%Morris County100.0%

Monitoring hubs

Ocean County809 sitesCape May County584 sitesMonmouth County485 sites

Lowest flow reads

Monmouth County31%Gloucester County33%Cumberland County47%

Highest fresh streamflow pipeline snapshots: Bergen County (228%, observation 2026), Morris County (226%, observation 2026), Passaic County (178%, observation 2026). These are source-data observations, not household tap-water conclusions.

All New Jersey Counties

CountySDWIS Compliance Index
Somerset County86.2
Union County86.2
Hudson County71.9
Gloucester County69.8
Bergen County68.5
Cape May County66.9
Ocean County66.9
Mercer County66.5
Atlantic County66.3
Essex County63.8
Camden County63.1
Burlington County62.9
Middlesex County62.6
Monmouth County62.3
Warren County60.3
Passaic County58.3
Morris County46.2
Cumberland County36.4
Hunterdon County29.7
Sussex County28.4
Salem County19.6

Frequently Asked Questions

Which New Jersey county has the highest SDWIS Compliance Index?
Somerset County has the highest SDWIS Compliance Index in the published New Jersey cohort at 86.2/100. This WaterByCounty relative comparison is not an EPA score and does not establish current conditions for a utility or address.
What does the Five-Year SDWIS Compliance Band mean?
The band is derived only from each county aggregation's recorded health-violation rate per 100,000 people served for the stated five-year source window. It is separate from the relative SDWIS Compliance Index and is not a current determination for a specific utility or address.
What does EPA ATTAINS report across New Jersey?
Across 14 published New Jersey county records with EPA ATTAINS data, 97 of 105 assessed water bodies are listed as impaired. This is a watershed assessment and does not describe finished household tap water.
Which USGS streamflow records are shown across New Jersey?
WaterByCounty has 19 fresh USGS pipeline snapshots in the published New Jersey cohort. Each county page shows its observation timestamp and year. A pipeline snapshot is not a continuously updated reading or a tap-water safety measure.
Where can New Jersey residents find current official information?
Review the applicable utility's Consumer Confidence Report, active notices, and the state drinking-water agency. WaterByCounty's county-level historical aggregations do not establish the current status of a specific utility, address, private well, or household plumbing system.
What does Water Quality Portal monitoring volume show in New Jersey?
The published county records contain 748,015 results from 4,981 monitoring locations in the site's five-year aggregation. Monitoring volume does not by itself indicate better or worse water quality.

Data Sources

Drinking-water compliance data from the EPA Safe Drinking Water Information System (SDWIS) via the ECHO enforcement database. The WaterByCounty SDWIS Compliance Index reflects the recorded rate and is not an EPA score.

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.

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