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Federal water data

County water report

Delaware County Water Report

Drinking-water compliance, watershed health, monitoring records, and river conditions for Delaware County, Pennsylvania.

Water grade

C

Water score

53.3

State rank

#13

of 67

Health violations

18

EPA SDWIS, 5-year lookback

Watershed impaired

0.0%

12,587 water bodies assessed

Monitoring sites

61

14,858 recent measurements

Live streamflow

50%

Brandywine Creek at Chadds Ford, PA

Water at a glance

Key Water Indicators for Delaware County

EPA SDWIS

Safety Grade

C

Score: 53.3 / 100

EPA SDWIS

Active Violations

18

5-year health-based lookback

EPA ATTAINS

Watershed Health

0% impaired

12,587 bodies assessed

USGS NWIS

Streamflow Snapshot

50% of mean

Brandywine Creek at Chadds Ford, PA

EPA WQP

Monitoring Sites

61

14,858 recent readings

Source: EPA SDWIS · Safe Drinking Water Information System

Drinking Water Compliance

Compliance grade

C

Based on EPA SDWIS compliance history.

Water score

Higher scores indicate cleaner recent compliance records.

53.3/100

Health violations

18

Health-based violations

Violations per 100K served

12.1

Population-normalized SDWIS rate

Editorial analysis

Understanding Delaware County’s Water

Drinking Water Quality Overview

EPA SDWIS

Delaware County's drinking water earned a C grade, scoring 53.3 out of 100. Over the past five years, EPA SDWIS records 18 health-based violations — a pattern that public water utilities are required to disclose and correct.

Watershed Conditions

EPA ATTAINS

Under the Clean Water Act §303(d), EPA ATTAINS tracks whether waterways meet quality standards for drinking, recreation, and aquatic life (reporting cycle: 2022). None of the assessed waterways are listed as impaired (0 of 12,587 water bodies) across Delaware County's watersheds. Impairment does not mean tap water is unsafe — it measures ambient waterway conditions upstream of treatment, not finished drinking water.

River & Streamflow Status

USGS NWIS

USGS NWIS gauge data (as of 2026-05-14T14:30:00.000-04:00) puts Brandywine Creek at 227.0 cfs — well below its long-term average at 50% of mean — low-flow conditions worth noting for water-dependent ecosystems. Streamflow is a leading indicator of drought stress, sediment load, and dilution capacity: low flows concentrate pollutants and warm water temperatures, stressing aquatic life and, in surface-water-dependent systems, the source water quality for treatment plants.

Monitoring Network

EPA WQP

EPA's Water Quality Portal (WQP) aggregates monitoring data from federal, state, and tribal agencies. Delaware County has extensive coverage with 61 active monitoring sites with 14,858 recent measurements on record. Predominant monitoring categories include physical and inorganics, minor, metals. More monitoring sites generally indicate greater scientific attention to local water conditions — and provide the baseline data that regulators use to set future impairment listings.

Editorial advisory

What the data suggests for Delaware County

Water Verdict

Delaware County receives a below-average water quality assessment with a grade of C and a score of 53.3 out of 100. Residents should review their utility's Consumer Confidence Report and may want to consider additional water filtration for drinking.

Violation Context

Delaware County has recorded 18 health-based violations, indicating multiple instances where federal contaminant limits or treatment requirements were not met. At 12.1 violations per 100,000 people served, this rate is high and signals significant water quality management issues.

Consumer Guidance

Tap water in Delaware County meets baseline standards but the compliance record shows room for improvement, with a Grade C rating. Delaware County's drinking-water compliance score is 53.3 out of 100. The violation rate for Delaware County is 12.1 per 100,000 people served. Residents who are immunocompromised, pregnant, or have young children may benefit from using an NSF 53-certified filter. Contacting your local utility for the current Consumer Confidence Report will confirm which specific violations were recorded and whether they have been resolved. With 61 active water-quality monitoring sites in Delaware County, data coverage is strong. A pipeline streamflow snapshot from the Brandywine Creek gauge is also available on this page.

Regional Context

Delaware County has better water quality than the average county in Pennsylvania. Its water score is 14.4 points higher than the state average, indicating stronger water system performance relative to neighboring counties.

Advisory text summarizes county-level public records and is not a replacement for your utility's current Consumer Confidence Report or direct local notices.

Contaminants & Resources

Key issues flagged in Delaware County's water environment

Official EPA Resources for Delaware County

EPA How's My Waterway

Interactive watershed health data for Delaware County

EPA ECHO: Drinking Water Systems

Search water utilities and violation records for Delaware County

Consumer Confidence Reports (PA)

Annual water quality reports from utilities in Pennsylvania

Clean Water Act §303(d)

Watershed Health

Impaired Water Bodies

0.0%

0 of 12,587 assessed

Mostly healthy

Top Impairment Causes

No specific impairment causes reported for the assessed water bodies in this county.

Source: EPA ATTAINS · Reporting cycle 2022

Impairment is determined under the Clean Water Act §303(d): a water body is impaired when it fails to meet state-defined quality standards for designated uses (drinking, recreation, aquatic life). Assessment coverage varies by state; counties without assessed water bodies are not shown.

Past 5 years

Water Quality Monitoring

Monitoring Sites

61

Active in the past 5 years

Measurements Recorded

15K

14,858 total readings

Most Measured

  • Physical
  • Inorganics, Minor, Metals
  • Organics, Pesticide

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

227cfs

May 14, 6:30 PM UTC

vs Long-Term Average

50%

Well below typical

Primary Streamgage

Brandywine Creek at Chadds Ford, PA

USGS site
01481000
Drainage area
287 sq mi
Long-term mean
454 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; the percent-of-typical value compares the latest reading against that average.

Free tool

Estimate Your Water Costs

Water Cost Estimate

3

3 people  ·  ~225 gal/day

Annual Total

$558

Monthly

$47

Water Bill

$558/yr

Filter Cost

$0/yr

Safety Grade for Delaware County:C — Moderate

Some violations or watershed impairment detected.

Estimates use the national average residential water rate ($0.0068/gal, EPA/AWWA 2023) and EPA WaterSense per-person consumption baseline (75 gal/person/day). Actual bills vary by utility, usage tier, and local infrastructure fees. For informational purposes only.

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Frequently Asked Questions

What is the water quality in Delaware County, Pennsylvania?
Delaware County, Pennsylvania has a drinking-water quality grade of C with a score of 53.3/100, based on EPA SDWIS compliance data. The county has 18 health-based drinking water violations over the past 5 years. Watershed health, monitoring records, and streamflow snapshots are reported separately on this page.
Are there any water violations in Delaware County?
Delaware County has 18 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 healthy are the watersheds in Delaware County?
EPA ATTAINS assessments under Clean Water Act §303(d) indicate 0.0% of Delaware County's 12,587 assessed water bodies are classified as impaired (0 impaired). Impairment means the water body fails to meet state quality standards for at least one designated use — drinking water source, recreation, aquatic life, or fish consumption. Note: watershed impairment doesn't always translate to tap-water issues; treatment plants can remove most regulated contaminants.
How much water-quality monitoring happens in Delaware County?
EPA's Water Quality Portal records 14,858 measurements from 61 monitoring sites in Delaware County over the past five years. The most frequently measured characteristic groups are Physical, Inorganics, Minor, Metals, Organics, Pesticide. 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 Delaware County right now?
Delaware County's primary USGS streamgage on the Brandywine Creek has a pipeline snapshot of 227 cubic feet per second — 50% of the long-term mean of 454.06 cfs. This is well below typical — often a signal of drought stress on source water. For the latest gauge feed, visit waterdata.usgs.gov.
How does Delaware County water compare to the Pennsylvania average?
Delaware County's SDWIS water quality score of 53.3/100 is higher than the Pennsylvania state average of 38.9. The average water quality grade across Pennsylvania is F, based on data from 67 counties with available SDWIS data.
Is tap water safe to drink in Delaware County?
Based on EPA SDWIS data, Delaware County has a water quality grade of C (53.3/100). 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 Delaware County have so many water violations?
Delaware County has 18 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 Delaware County rank for water quality in Pennsylvania?
Delaware County ranks #13 out of 67 counties in Pennsylvania by SDWIS water quality score (1 = best). With a score of 53.3/100, it falls in the top 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

Lawrence County

Pennsylvania

C

52.5

Water score

Berks County

Pennsylvania

C

52.0

Water score

Lebanon County

Pennsylvania

C

54.8

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.

Watershed health and impaired-waterway data from the EPA ATTAINS Clean Water Act §303(d) assessments, state-reported and EPA-finalized.

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 Evan Brooks, Data EditorUpdated Reviewed by Evan Brooks, Data Editor

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