Onset, MA 02558

1 water system • 5,392 residents

Moderate water quality - consider filtration

C

Score: 55/100

Graded on EPA violations, contaminants, severity, compliance, and enforcement history. See methodology.

Data updated June 2026 • Sources: EPA ECHO and EPA Envirofacts

34

Contaminants Detected

72

Violations on Record

16

Health-Based Violations

0

Recent Violations

Grade Breakdown

Contaminant Count0 / 25
Violation History16 / 25
Contaminant Severity5 / 25
System Compliance0 / 15
Enforcement History0 / 10
Total Score55%

55 / 100 points

Recommended Water Filters

  • ✓Point-of-Use Carbon Filter (NSF-certified for lead)
  • ✓Reverse Osmosis or Ion Exchange Filter
  • ✓Ultraviolet (UV) Purification
Compare filter types in our Filter Guide →

Consult a water quality specialist for personalized recommendations.

Onset vs MA & National Average

Detected Contaminants

34 contaminants detected across water systems serving this ZIP code

ContaminantCategory
NitrateAgricultural
Lead and Copper RuleHeavy Metal
Coliform (TCR)Microorganism
Revised Total Coliform RuleMicroorganism
1,1,1-TrichloroethaneOther
1,1,2-TrichloroethaneOther
1,2-DIBROMO-3-CHLOROPROPANEOther
1,2-DichloropropaneOther
2,4-DOther
2,4,5-TPOther
BHC-GAMMAOther
Consumer Confidence RuleOther
DICHLOROMETHANEOther
EndrinOther
ETHYLENE DIBROMIDEOther
MethoxychlorOther
ToxapheneOther
1,1-DichloroethyleneVolatile Organic
1,2-DichloroethaneVolatile Organic
1,2,4-TrichlorobenzeneVolatile Organic
BenzeneVolatile Organic
Carbon tetrachlorideVolatile Organic
CHLOROBENZENEVolatile Organic
cis-1,2-DichloroethyleneVolatile Organic
EthylbenzeneVolatile Organic
o-DichlorobenzeneVolatile Organic
p-DichlorobenzeneVolatile Organic
StyreneVolatile Organic
TetrachloroethyleneVolatile Organic
TolueneVolatile Organic
trans-1,2-DichloroethyleneVolatile Organic
TrichloroethyleneVolatile Organic
Vinyl chlorideVolatile Organic
Xylenes, TotalVolatile Organic

Water System Information

Systems Serving This ZIP:
ONSET FIRE DISTRICTWATER DEPT.
Population Served:
5,392
Systems With Violations:
1 of 1
Major Violations:
7
Enforcement Actions:
49

Nearby Areas

02571

Wareham • 2.1 mi away

A

02532

Buzzards Bay • 3.5 mi away

A

02559

Pocasset • 4.1 mi away

B

02738

Marion • 5 mi away

B

02562

Sagamore Beach • 7.8 mi away

B

02542

Buzzards Bay • 8.5 mi away

A

Frequently Asked Questions

What does the grade mean?

Our A–F grade ranks this ZIP code's water quality against every other analyzed ZIP in the country, based on EPA data. A = among the best, F = among the most troubled.

Is my tap water safe to drink?

Water systems regulated by the EPA must comply with Safe Drinking Water Act standards. However, if you're concerned about water quality, consider a water filter appropriate for your contaminants.

How often is the data updated?

We update our data quarterly with the latest EPA ECHO and Envirofacts data. Historical violations are tracked to identify patterns.

What filters do you recommend?

Filter recommendations are based on detected contaminants in your area. See our Filter Guide for detailed information about different filter types.