Head-to-head water quality

Boston, MA vs Bryn Mawr, PA

Side-by-side water quality comparison: Boston (Grade B) vs Bryn Mawr (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

Boston

Bryn Mawr

Better

Violations subscore / 45

42.8

0.0

Boston

Lead/Copper subscore / 20

6.0

16.0

Bryn Mawr

Contaminant subscore / 20

19.0

4.2

Boston

Compliance subscore / 10

5.0

10.0

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

Boston

Bryn Mawr

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

Bryn Mawr

PFAS — "forever chemicals"

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

Factor

Boston

Bryn Mawr

Better

PFAS analytes detected

0 of 30

10 of 30

Boston

PFAS exceeds federal MCL

Yes

Boston

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

Boston

Bryn Mawr

Better

Violations (last 5 years)

147

Boston

Health-based violations (total)

Boston

Unresolved violations

Boston

Other contaminants tested

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

Factor

Boston

Bryn Mawr

Better

Chromium-6 (max)

—

2.60 µg/L

Bryn Mawr

HAA5 (avg)

15.35 µg/L

25.99 µg/L

Boston

Manganese (max)

10.90 µg/L

81.00 µg/L

Boston

Strontium (max)

39.40 µg/L

817.00 µg/L

Boston

1,4-Dioxane (max)

—

2.20 µg/L

Bryn Mawr

NDMA (max)

3.88 ng/L

15.00 ng/L

Boston

Vanadium (max)

—

2.10 µg/L

Bryn Mawr

Chlorate (max)

220.00 µg/L

838.00 µg/L

Boston

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

Boston

Bryn Mawr

Better

Superfund sites within 10 mi

Boston

TRI lbs to surface water within 10 mi (2023)

Bryn Mawr

System size & source

Factor

Boston

Bryn Mawr

Population served

3.3M

1.1M

—

Water source

Surface water

—

Number of water systems

—

See the full reports

Full report

Boston, MA water quality

Grade B · 3.3M served

Full report

Bryn Mawr, PA water quality

Grade F · 1.1M served

All cities in Massachusetts → All cities in Pennsylvania →

Frequently asked

Which has better water — Boston or Bryn Mawr?

Boston, MA scores higher (76.8 vs 34.2) on WaterVerge's 100-point methodology, earning a Grade B 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.