Head-to-head water quality

Bryn Mawr, PA vs Seattle, WA

Side-by-side water quality comparison: Bryn Mawr (Grade F) vs Seattle (Grade F). Lead, PFAS, violations, and source-water contamination

Score breakdown

Each factor is shown as raw points (out of the maximum). Higher = better.

Factor

Bryn Mawr

Seattle

Better

Violations subscore / 45

0.0

Tie

Lead/Copper subscore / 20

16.0

Tie

Contaminant subscore / 20

4.2

14.3

Seattle

Compliance subscore / 10

10.0

8.0

Bryn Mawr

Source subscore / 5

4.0

Tie

Lead & copper at the tap

Lead and Copper Rule (LCR) 90th-percentile readings — the value that 10% of sampled homes exceed.

Factor

Bryn Mawr

Seattle

Better

Lead 90th-percentile (latest) · EPA action level: 15 µg/L

0.0 µg/L

Bryn Mawr

Copper 90th-percentile (latest) · EPA action level: 1.3 mg/L

1.4 mg/L

610.0 mg/L

Bryn Mawr

PFAS — "forever chemicals"

UCMR 5 testing, 2023–2025. Federal MCLs: PFOA + PFOS = 4 ng/L; HFPO-DA = 10 ng/L.

Factor

Bryn Mawr

Seattle

Better

PFAS analytes detected

10 of 30

0 of 30

Seattle

PFAS exceeds federal MCL

Yes

Seattle

PFAS hazard index · Sum of (max/MCL) across detected analytes; > 1 indicates exceedance

9.43

—

Bryn Mawr

Violation history

SDWA enforcement actions — fewer is better.

Factor

Bryn Mawr

Seattle

Better

Violations (last 5 years)

147

270

Bryn Mawr

Health-based violations (total)

138

Bryn Mawr

Unresolved violations

120

Bryn Mawr

Other contaminants tested

UCMR rounds 1–4 + UCMR 5 lithium. Maxima where data exists; "—" means not tested.

Factor

Bryn Mawr

Seattle

Better

Chromium-6 (max)

2.60 µg/L

0.20 µg/L

Seattle

HAA5 (avg)

25.99 µg/L

24.10 µg/L

Seattle

Manganese (max)

81.00 µg/L

6.50 µg/L

Seattle

Strontium (max)

817.00 µg/L

38.00 µg/L

Seattle

1,4-Dioxane (max)

2.20 µg/L

—

Bryn Mawr

NDMA (max)

15.00 ng/L

—

Bryn Mawr

Vanadium (max)

2.10 µg/L

0.97 µg/L

Seattle

Chlorate (max)

838.00 µg/L

61.00 µg/L

Seattle

Molybdenum (max)

8.50 µg/L

—

Bryn Mawr

Industrial proximity

Superfund National Priorities List + Toxic Release Inventory facilities within 10 miles of the city centroid.

Factor

Bryn Mawr

Seattle

Better

Superfund sites within 10 mi

Seattle

TRI lbs to surface water within 10 mi (2023)

Seattle

System size & source

Factor

Bryn Mawr

Seattle

Population served

1.1M

1.2M

—

Water source

Surface water

—

Number of water systems

—

See the full reports

Full report

Bryn Mawr, PA water quality

Grade F · 1.1M served

Full report

Seattle, WA water quality

Grade F · 1.2M served

All cities in Pennsylvania → All cities in Washington →

Frequently asked

Which has better water — Bryn Mawr or Seattle?

Seattle, WA scores higher (42.3 vs 34.2) on WaterVerge's 100-point methodology, earning a Grade F compared to Bryn Mawr's Grade F. The score combines violation history, lead and copper levels, contaminant testing, monitoring compliance, and source-water type.

How is the WaterVerge water quality score calculated?

The grade combines five subscores: violation history (45 pts, weighted by recency and health-based severity), lead/copper 90th-percentile vs EPA action levels (20 pts), contaminant testing including PFAS, chromium-6, HAA5, NDMA, perchlorate, and Superfund/TRI proximity (20 pts), monitoring compliance (10 pts), and water-source-type risk (5 pts). Full methodology at /about/methodology.

Where does this water quality data come from?

From the EPA's public records: the SDWIS bulk download (violations + system info), UCMR rounds 1–5 (unregulated contaminant testing including PFAS, chromium-6, HAA5, NDMA, perchlorate, vanadium, lithium), the EPA Toxic Release Inventory (industrial polluters), the Superfund National Priorities List, the USGS Powell Domestic-Well Database (private-well chemistry), and the CDC Community Water Fluoridation system. Data is refreshed quarterly.