waterbycounty
Compiled federal source snapshot

Pennsylvania Water Quality

Drinking water data for all 67 counties.

Avg SDWIS Compliance Index

41.7

Most Common Five-Year SDWIS Compliance Band

F

Counties with Data

67

of 67 total

County water atlas

Pennsylvania 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

67

Avg SDWIS index

41.7

Watersheds

67

ATTAINS counties

Monitoring

67

64 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 Pennsylvania

Beyond Drinking Water

EPA SDWIS

67/ 67

counties with drinking-water compliance data

1,110 health violations statewide (5yr)

EPA ATTAINS

34.1%

avg impaired across 67 counties

543,625 of 1,604,506 assessed bodies impaired

EPA WQP

3,723

monitoring sites across 67 counties

998,048 total readings (5yr window)

USGS NWIS

64

counties with a fresh pipeline snapshot

5 above54 below

State atlas notes

What stands out in Pennsylvania

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

Cameron County has the highest value in the published state SDWIS Compliance Index table at 86.2/100, while Wyoming County has the lowest at 7.3/100. That is a 78.9 point gap inside one state.

Zero health violations

4

3+ health violations

58

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.

Montgomery County72.7%Philadelphia County71.1%Delaware County68.9%

Monitoring hubs

Lancaster County210 sitesBucks County181 sitesChester County179 sites

Lowest flow reads

Fulton County3%Erie County11%Crawford County12%

Highest fresh streamflow pipeline snapshots: Bucks County (273%, observation 2026), Jefferson County (200%, observation 2026), Blair County (147%, observation 2026). These are source-data observations, not household tap-water conclusions.

All Pennsylvania Counties

CountySDWIS Compliance Index
Cameron County86.2
Forest County86.2
Fulton County86.2
Philadelphia County86.2
Montgomery County70.7
Lehigh County67.4
Westmoreland County66.9
Cumberland County66.5
Allegheny County65.6
Northumberland County65.1
Mifflin County62.6
Bucks County61.0
Lebanon County58.9
Delaware County57.3
Somerset County56.9
Dauphin County56.5
Blair County55.9
Northampton County54.3
York County54.1
Clearfield County53.5
Berks County52.5
Adams County51.8
Lawrence County51.1
Centre County49.7
Erie County49.3
Lackawanna County49.1
Fayette County48.1
Butler County47.8
Lancaster County47.5
Luzerne County47.2
Franklin County46.2
Huntingdon County46.0
Chester County44.9
Jefferson County43.7
Schuylkill County43.2
Bradford County41.8
Columbia County41.5
Montour County39.3
Greene County38.8
Clinton County38.3
Snyder County37.7
Beaver County36.7
Elk County34.1
Cambria County30.6
Union County29.0
Mercer County28.2
Tioga County26.4
Lycoming County24.8
Venango County22.7
Pike County22.4
Clarion County22.3
Crawford County21.7
Susquehanna County21.4
Potter County19.5
Washington County19.3
Indiana County19.2
Carbon County17.2
Monroe County17.1
Armstrong County15.6
Warren County15.1
Juniata County12.9
McKean County12.7
Perry County11.4
Bedford County11.3
Wayne County10.4
Sullivan County9.0
Wyoming County7.3

Frequently Asked Questions

Which Pennsylvania county has the highest SDWIS Compliance Index?
Cameron County has the highest SDWIS Compliance Index in the published Pennsylvania 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 Pennsylvania?
Across 67 published Pennsylvania county records with EPA ATTAINS data, 543,625 of 1,604,506 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 Pennsylvania?
WaterByCounty has 64 fresh USGS pipeline snapshots in the published Pennsylvania 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 Pennsylvania 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 Pennsylvania?
The published county records contain 998,048 results from 3,723 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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