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F0/100

SIASCONSET WATER DEPARTMENT — Water Quality Report 2026

Serving 3,000 people · Massachusetts

Water Source

Groundwater

County

—

System ID

MA4197001

Violations

76

Contaminant Test Results

1 contaminant above EPA health goals

Contaminant	Detected	Limit (MCL)	Goal (MCLG)	Status
Copper (90th percentile)	1.49 mg/L	1.30 mg/L	1.30 mg/L	Over Limit

EPA Violation History

32

Violations (last 5yr)

31

Unresolved

0

Health-Related

TIER 3Unresolved

Exceeded the MCL for disinfection byproducts

This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.

When: April 1, 2025 – June 30, 2025Enforcement: Formal — state order issuedVerify on EPA.gov

TIER 3Unresolved

Exceeded the MCL for disinfection byproducts

This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.

When: April 1, 2024 – June 30, 2024Enforcement: Formal — state order issuedVerify on EPA.gov

TIER 3Unresolved

Exceeded the MCL for disinfection byproducts

This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.

When: April 1, 2024 – June 30, 2024Enforcement: Formal — state order issuedVerify on EPA.gov

TIER 3Unresolved

Exceeded the MCL for disinfection byproducts

This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.

When: April 1, 2024 – June 30, 2024Enforcement: Formal — state order issuedVerify on EPA.gov

TIER 3Unresolved

Exceeded the MCL for disinfection byproducts

This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.

When: April 1, 2024 – June 30, 2024Enforcement: Formal — state order issuedVerify on EPA.gov

TIER 3Unresolved

Exceeded the MCL for disinfection byproducts

This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.

When: April 1, 2024 – June 30, 2024Enforcement: Formal — state order issuedVerify on EPA.gov

TIER 3Unresolved

Exceeded the MCL for disinfection byproducts

This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.

When: April 1, 2024 – June 30, 2024Enforcement: Formal — state order issuedVerify on EPA.gov

TIER 3Unresolved

Exceeded the MCL for disinfection byproducts

This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.

When: April 1, 2024 – June 30, 2024Enforcement: Formal — state order issuedVerify on EPA.gov

TIER 3Unresolved

Exceeded the MCL for disinfection byproducts

This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.

When: April 1, 2024 – June 30, 2024Enforcement: Formal — state order issuedVerify on EPA.gov

TIER 3Unresolved

Exceeded the MCL for disinfection byproducts

This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.

When: April 1, 2024 – June 30, 2024Enforcement: Formal — state order issuedVerify on EPA.gov

TIER 3Unresolved

Exceeded the MCL for disinfection byproducts

This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.

When: April 1, 2024 – June 30, 2024Enforcement: Formal — state order issuedVerify on EPA.gov

TIER 3Unresolved

Exceeded the MCL for disinfection byproducts

This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.

When: April 1, 2024 – June 30, 2024Enforcement: Formal — state order issuedVerify on EPA.gov

TIER 3Unresolved

Exceeded the MCL for disinfection byproducts

This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.

When: April 1, 2024 – June 30, 2024Enforcement: Formal — state order issuedVerify on EPA.gov

TIER 3Unresolved

Exceeded the MCL for disinfection byproducts

This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.

When: April 1, 2024 – June 30, 2024Enforcement: Formal — state order issuedVerify on EPA.gov

TIER 3Unresolved

Exceeded the MCL for disinfection byproducts

This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.

When: April 1, 2024 – June 30, 2024Enforcement: Formal — state order issuedVerify on EPA.gov

TIER 3Unresolved

Exceeded the MCL for disinfection byproducts

This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.

When: April 1, 2024 – June 30, 2024Enforcement: Formal — state order issuedVerify on EPA.gov

TIER 3Unresolved

Exceeded the MCL for disinfection byproducts

This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.

When: April 1, 2024 – June 30, 2024Enforcement: Formal — state order issuedVerify on EPA.gov

TIER 3Unresolved

Exceeded the MCL for disinfection byproducts

This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.

When: April 1, 2024 – June 30, 2024Enforcement: Formal — state order issuedVerify on EPA.gov

TIER 3Unresolved

Exceeded the MCL for disinfection byproducts

This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.

When: April 1, 2024 – June 30, 2024Enforcement: Formal — state order issuedVerify on EPA.gov

TIER 3Unresolved

Exceeded the MCL for disinfection byproducts

This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.

When: April 1, 2024 – June 30, 2024Enforcement: Formal — state order issuedVerify on EPA.gov

TIER 3Unresolved

Exceeded the MCL for disinfection byproducts

This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.

When: April 1, 2024 – June 30, 2024Enforcement: Formal — state order issuedVerify on EPA.gov

TIER 3Unresolved

Exceeded the MCL for disinfection byproducts

This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.

When: April 1, 2024 – June 30, 2024Enforcement: Formal — state order issuedVerify on EPA.gov

TIER 3Unresolved

Exceeded the MCL for disinfection byproducts

This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.

When: April 1, 2024 – June 30, 2024Enforcement: Formal — state order issuedVerify on EPA.gov

TIER 3Unresolved

Exceeded the MCL for disinfection byproducts

This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.

When: April 1, 2024 – June 30, 2024Enforcement: Formal — state order issuedVerify on EPA.gov

TIER 3Unresolved

Exceeded the MCL for disinfection byproducts

This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.

When: April 1, 2024 – June 30, 2024Enforcement: Formal — state order issuedVerify on EPA.gov

TIER 3Unresolved

Exceeded the MCL for disinfection byproducts

This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.

When: April 1, 2024 – June 30, 2024Enforcement: Formal — state order issuedVerify on EPA.gov

TIER 3Unresolved

Exceeded the MCL for disinfection byproducts

This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.

When: April 1, 2024 – June 30, 2024Enforcement: Formal — state order issuedVerify on EPA.gov

TIER 3Unresolved

Exceeded the MCL for disinfection byproducts

This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.

When: April 1, 2024 – June 30, 2024Enforcement: Formal — state order issuedVerify on EPA.gov

TIER 3Unresolved

Exceeded the MCL for disinfection byproducts

This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.

When: April 1, 2024 – June 30, 2024Enforcement: Formal — state order issuedVerify on EPA.gov

TIER 3Unresolved

Exceeded the MCL for disinfection byproducts

This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.

When: April 1, 2024 – June 30, 2024Enforcement: Formal — state order issuedVerify on EPA.gov

TIER 3Unresolved

Exceeded the MCL for disinfection byproducts

This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.

When: April 1, 2024 – June 30, 2024Enforcement: Formal — state order issuedVerify on EPA.gov

TIER 3Resolved

Surface water treatment technique failure

When: July 1, 2022 – August 15, 2022Enforcement: Formal — state order issued

Understanding violation severity

Tier 1Urgent health risk. Utility must notify all customers within 24 hours.Tier 2Important health or treatment issue. Customers notified within 30 days.Tier 3Administrative or monitoring issue. Reported in the annual water quality report.

Source: EPA Safe Drinking Water Information System (SDWIS) · Updated quarterly

Frequently Asked Questions About SIASCONSET WATER DEPARTMENT

Is SIASCONSET WATER DEPARTMENT water safe to drink?

SIASCONSET WATER DEPARTMENT water receives a grade of F (0/100), which is considered failing. 1 contaminant(s) exceed EPA legal limits and 76 violation(s) are on record. Customers may want to consider using a water filter.

What contaminants has SIASCONSET WATER DEPARTMENT detected?

2 contaminants were tested in SIASCONSET WATER DEPARTMENT's water. Notable contaminants include Copper (90th percentile). 1 exceed EPA legal limits (MCLs). 1 exceed EPA health goals (MCLGs).

Does SIASCONSET WATER DEPARTMENT have any EPA violations?

Yes, SIASCONSET WATER DEPARTMENT has 76 EPA violation(s) on record, with the most recent in 2025. Violation types include MR, Other, MCL. 4 are health-based violations.

How many people does SIASCONSET WATER DEPARTMENT serve?

SIASCONSET WATER DEPARTMENT serves approximately 3,000 people, Massachusetts. The system provides water to 1 community: Nantucket.

What type of water does SIASCONSET WATER DEPARTMENT provide?

SIASCONSET WATER DEPARTMENT sources its water from groundwater. Groundwater is pumped from underground aquifers, which often provides natural filtration. The utility's system ID is MA4197001.

How does SIASCONSET WATER DEPARTMENT compare to other utilities in Massachusetts?

SIASCONSET WATER DEPARTMENT scores 0/100 with a grade of F (failing). This score suggests significant water quality concerns relative to other utilities. Visit our Massachusetts state page for a full comparison of water systems.

Cities Served