Head-to-head water quality

Baltimore, MD vs Phoenix, AZ

Side-by-side water quality comparison: Baltimore (Grade F) vs Phoenix (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

Baltimore

Phoenix

Better

Violations subscore / 45

0.8

0.0

Baltimore

Lead/Copper subscore / 20

16.0

Tie

Contaminant subscore / 20

13.9

9.5

Baltimore

Compliance subscore / 10

5.0

8.0

Phoenix

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

Baltimore

Phoenix

Better

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

0.0 µg/L

Baltimore

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

2.1 mg/L

1.9 mg/L

Phoenix

PFAS — "forever chemicals"

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

Factor

Baltimore

Phoenix

Better

PFAS analytes detected

1 of 30

3 of 30

Baltimore

PFAS exceeds federal MCL

Tie

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

—

Violation history

SDWA enforcement actions — fewer is better.

Factor

Baltimore

Phoenix

Better

Violations (last 5 years)

210

Baltimore

Health-based violations (total)

Baltimore

Unresolved violations

198

Baltimore

Other contaminants tested

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

Factor

Baltimore

Phoenix

Better

Chromium-6 (max)

0.09 µg/L

54.00 µg/L

Baltimore

HAA5 (avg)

43.55 µg/L

8.77 µg/L

Phoenix

Manganese (max)

1.58 µg/L

992.00 µg/L

Baltimore

Strontium (max)

96.10 µg/L

1140.00 µg/L

Baltimore

Perchlorate (max)

—

5.20 µg/L

Phoenix

Vanadium (max)

0.29 µg/L

23.20 µg/L

Baltimore

Chlorate (max)

233.00 µg/L

884.00 µg/L

Baltimore

Molybdenum (max)

—

5.40 µg/L

Phoenix

Industrial proximity

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

Factor

Baltimore

Phoenix

Better

Superfund sites within 10 mi

Phoenix

TRI lbs to surface water within 10 mi (2023)

63,295

Phoenix

System size & source

Factor

Baltimore

Phoenix

Population served

1.6M

1.7M

—

Water source

Surface water

—

Number of water systems

—

See the full reports

Full report

Baltimore, MD water quality

Grade F · 1.6M served

Full report

Phoenix, AZ water quality

Grade F · 1.7M served

All cities in Maryland → All cities in Arizona →

Frequently asked

Which has better water — Baltimore or Phoenix?

Baltimore, MD scores higher (39.8 vs 37.5) on WaterVerge's 100-point methodology, earning a Grade F compared to Phoenix'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.