waterbycounty
Federal water data

County water report

Prince William County Water Report

Drinking-water compliance, watershed health, monitoring records, and river conditions for Prince William County, Virginia.

Water grade

A

Water score

70.6

State rank

#45

of 95

Health violations

3

EPA SDWIS, 5-year lookback

Watershed impaired

49.3%

138 water bodies assessed

Monitoring sites

28

13,089 recent measurements

Live streamflow

40%

S F QUANTICO CREEK NEAR INDEPENDENT HILL, VA

Water at a glance

Key Water Indicators for Prince William County

EPA SDWIS

Safety Grade

A

Score: 70.6 / 100

EPA SDWIS

Active Violations

3

5-year health-based lookback

EPA ATTAINS

Watershed Health

49% impaired

138 bodies assessed

USGS NWIS

Streamflow Snapshot

40% of mean

S F QUANTICO CREEK NEAR INDEPENDENT HILL, VA

EPA WQP

Monitoring Sites

28

13,089 recent readings

Source: EPA SDWIS · Safe Drinking Water Information System

Drinking Water Compliance

Compliance grade

A

Based on EPA SDWIS compliance history.

Water score

Higher scores indicate cleaner recent compliance records.

70.6/100

Health violations

3

Health-based violations

Violations per 100K served

0.7

Population-normalized SDWIS rate

Data center water stress

Prince William County has 85 facilities in the DCWSI dataset.

ByCounty's DCWSI ranks this county #14 nationally by combining its water score with mapped data center density.

DCWSIThe Data Center Water Stress Index: 60% the county's water-system stress plus 40% how concentrated data centers already are, scored 0-100. Higher means data-center density and water pressure overlap more here.

82.1

0-100 index

Facility count

85

99.4 density percentile

Discharge estimate

Not reported

EPA CWA fields where available

Water vs median

+20.6

Compared with US county median

Named operators

AWSGoogleMicrosoft

Mapped facilities

  • AMAZON DATA SERVICES (IAD-130, IAD-131, IAD-313, AND DCA-072)

    MANASSAS · Amazon Data Services

    EPA ECHO

  • AMAZON DATA SERVICES INC - IAD-104/105/106

    MANASSAS · Amazon Data Services

    EPA ECHO

  • AMAZON DATA SERVICES INC IAD-195/196/197/198

    GAINESVILLE · Amazon Data Services

    EPA ECHO

  • AMAZON DATA SERVICES INC IAD-210/211

    MANASSAS · Amazon Data Services

    EPA ECHO

  • AMAZON DATA SERVICES, INC IAD-132/133

    MANASSAS · Amazon Data Services

    EPA ECHO

  • AMAZON DATA SERVICES, INC. IAD-55 IAD-64 IAD-84

    HAYMARKET · Amazon Data Services

    EPA ECHO

79 more mapped facilities included in the county score.

See the Prince William County data-center reportReview methodology

Data Center Water Budget Calculator

Estimate daily water use for a hypothetical facility in Prince William County.

1 MW1,000 MW
40%100%
799K gallons/dayHigh Impact

Your facility would use 157.0% of this county's industrial water baseline. Verify water rights and long-term drought projections before committing.

157.0% of county industrial baseline

Based on USGS 2020 water-use data and EPA-standard cooling intensity constants. Not a substitute for site-specific water rights analysis.

Editorial analysis

Understanding Prince William County’s Water

Drinking Water Quality Overview

EPA SDWIS

Prince William County earns an A grade for drinking water quality, scoring 70.6 out of 100. Over the past five years, EPA SDWIS records 3 health-based violations — a small cluster that warrants attention.

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). A substantial 49.3% of assessed waterways are impaired (68 of 138 water bodies) across Prince William County's watersheds. The leading impairment causes are escherichia coli (e. coli) and pcbs in fish tissue. 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 2026-05-14T14:15:00.000-04:00) puts S F QUANTICO CREEK at 2.8 cfs — well below its long-term average at 40% 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. Prince William County has moderate coverage with 28 active monitoring sites with 13,089 recent measurements on record. Predominant monitoring categories include physical and nutrient. 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 Prince William County

Water Verdict

Prince William County, Virginia receives a good water quality assessment with a grade of A and a score of 70.6 out of 100. While the water supply is generally safe, occasional monitoring gaps or minor contaminant detections may occur. Separately, EPA ATTAINS assessments cover 138 water bodies in the county's watershed, with 49.3% listed as impaired under the Clean Water Act — a source-water measure that is tracked independently of tap-water compliance. At the most recent USGS reading, local streamflow was below its historical mean at 39.5% — worth watching in drier seasons.

Violation Context

EPA SDWIS records for Prince William County, Virginia show 3 health-based violations, indicating multiple instances where federal contaminant limits or treatment requirements were not met. At 0.7 violations per 100,000 people served, this rate is relatively low compared to many U.S. counties. This compliance record sits alongside an unusually deep monitoring archive: 13,089 water-quality results have been logged across the county in the EPA Water Quality Portal over the past five years.

Consumer Guidance

Tap water in Prince William County earns a Grade A overall with a small number of isolated health violations in the recent record. Prince William County's drinking-water compliance score is 70.6 out of 100. The violation rate for Prince William County is 0.7 per 100,000 people served. These violations were likely resolved quickly; Grade A reflects a strong multi-year compliance trend. Reviewing the most recent Consumer Confidence Report will show exactly which systems were affected and what corrective action was taken. With 28 active water-quality monitoring sites in Prince William County, data coverage is strong. E. coli is the leading impairment cause in Prince William County's watershed. A pipeline streamflow snapshot from the S F QUANTICO CREEK gauge is also available on this page.

Regional Context

Prince William County has better water quality than the average county in Virginia. Its water score is 12.9 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 Prince William County's water environment

Watershed Impairment Causes (EPA ATTAINS)

  • 1

    E. coli (bacteria)

    Impairment cause per EPA Clean Water Act §303(d) assessment

  • 2

    Pcbs in Fish Tissue

    Impairment cause per EPA Clean Water Act §303(d) assessment

  • 3

    Low dissolved oxygen

    Impairment cause per EPA Clean Water Act §303(d) assessment

Source: EPA ATTAINS · Reporting cycle 2022

Official EPA Resources for Prince William County

EPA How's My Waterway

Interactive watershed health data for Prince William County

EPA ECHO: Drinking Water Systems

Search water utilities and violation records for Prince William County

Consumer Confidence Reports (VA)

Annual water quality reports from utilities in Virginia

Clean Water Act §303(d)

Watershed Health

Impaired Water Bodies

49.3%

68 of 138 assessed

Moderate concern

Top Impairment Causes

  • 1

    ESCHERICHIA COLI (E. COLI)

  • 2

    PCBS IN FISH TISSUE

  • 3

    DISSOLVED OXYGEN

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

28

Active in the past 5 years

Measurements Recorded

13K

13,089 total readings

Most Measured

  • Physical
  • Nutrient
  • 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

2.81cfs

May 14, 6:15 PM UTC

vs Long-Term Average

40%

Well below typical

Primary Streamgage

S F QUANTICO CREEK NEAR INDEPENDENT HILL, VA

USGS site
01658500
Drainage area
7.62 sq mi
Long-term mean
7.12 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 Prince William 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.

Try the full calculator →

Improve your water quality at home

Berkey filters remove 99.9%+ of contaminants from tap water.

Shop Berkey →

Sponsored

Test your tap water

Tap Score provides professional mail-in water testing.

Get Tested →

Frequently Asked Questions

What is the water quality in Prince William County, Virginia?
Prince William County, Virginia has a drinking-water quality grade of A with a score of 70.6/100, based on EPA SDWIS compliance data. The county has 3 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 Prince William County?
Prince William County has 3 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 Prince William County?
EPA ATTAINS assessments under Clean Water Act §303(d) indicate 49.3% of Prince William County's 138 assessed water bodies are classified as impaired (68 impaired). The top reported causes are ESCHERICHIA COLI (E. COLI), PCBS IN FISH TISSUE, DISSOLVED OXYGEN. 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 Prince William County?
EPA's Water Quality Portal records 13,089 measurements from 28 monitoring sites in Prince William County over the past five years. The most frequently measured characteristic groups are Physical, Nutrient, 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 Prince William County right now?
Prince William County's primary USGS streamgage on the S F QUANTICO CREEK has a pipeline snapshot of 2.81 cubic feet per second — 40% of the long-term mean of 7.12 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 Prince William County water compare to the Virginia average?
Prince William County's SDWIS water quality score of 70.6/100 is higher than the Virginia state average of 57.7. The average water quality grade across Virginia is D, based on data from 95 counties with available SDWIS data.
Is tap water safe to drink in Prince William County?
Based on EPA SDWIS data, Prince William County has a water quality grade of A (70.6/100). This indicates good to excellent water quality with strong SDWIS compliance. 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).
Does Prince William County have clean drinking water?
Prince William County has 3 health-based drinking water violations according to EPA records. With a water quality score of 70.6/100 and grade A, the county's drinking water has had some compliance issues but continues to be monitored. Note: drinking-water compliance speaks to the public water system, not necessarily to the watershed itself — check the Watershed Health zone for ATTAINS §303(d) data.
How does Prince William County rank for water quality in Virginia?
Prince William County ranks #45 out of 95 counties in Virginia by SDWIS water quality score (1 = best). With a score of 70.6/100, 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

Montgomery County

Virginia

B

69.0

Water score

Loudoun County

Virginia

B

68.6

Water score

Spotsylvania County

Virginia

B

66.0

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.

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

Explore more data for Prince William County

Property TaxCost of LivingCrime RateIncomeHealthSchoolsDisaster RiskWeatherCounty Score