Public water system · MA4197001
ActiveSiasconset Water Department
At a glance
Siasconset Water Department (PWSID MA4197001) is an active community water system in Nantucket County, Massachusetts. It reports serving 3,000 people through 863 service connections. Its primary water source is groundwater, and EPA lists it as owned by a local government. Of the 12 most recent violations in EPA's records, none is health-based, and the most recent began in July 2025.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
3,000
Service connections
863
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does Siasconset Water Department compare with other water systems in Nantucket County?
By EPA's size categories, Siasconset Water Department is a small system (501 to 3,300 people). Nantucket County has 5 active public water systems, and Siasconset Water Department is the 2nd-largest of them by population served. Its population served is about half of the county average of 6,513 people per system, and accounts for 9.2% of the 32,563 people reported by systems filed under the county. Across Massachusetts, the 1,636 active systems average 6,275 people each. Nationally, the average active community water system reports serving 6,703 people, so Siasconset Water Department is about 55% below that figure.
What does “community water system” mean?
A community water system serves at least 15 connections used by year-round residents, or regularly serves at least 25 year-round residents. Homes, apartments and mobile-home parks are served by these. Massachusetts has 531 active community water systems, 32% of the state's 1,636 active systems. Groundwater means the system draws its water from wells or springs fed by underground aquifers. 1,354 Massachusetts systems (83%) list groundwater as their primary source.
Who owns and regulates Siasconset Water Department?
EPA lists Siasconset Water Department as owned by a local government. The MA state drinking water program is its primacy agency, the regulator with primary enforcement responsibility for the system under the Safe Drinking Water Act. 3 of the 5 active systems in Nantucket County (60%) are also owned by a local government.
Does Siasconset Water Department have drinking water violations?
Of the 12 most recent violations in EPA's records, none is health-based, and the most recent began in July 2025. The violations listed here began between April 2024 and July 2025. By type: 11 monitoring and reporting and 1 public notice, recordkeeping or other. The contaminants or rules involved are Consumer Confidence Rule, Nitrate, Endothall and 1,2-Dibromo-3-chloropropane (DBCP). EPA lists 11 as archived and 1 as unaddressed. Archived means the violation was not marked resolved but is more than five years past the end of the noncompliance period, so it no longer counts toward current compliance status. Unaddressed means the violation is not resolved or archived and is not yet covered by formal enforcement.
| Began | Violation | Contaminant or rule | Health-based | Status |
|---|---|---|---|---|
| 2025-07-02 | Public notice, recordkeeping or otherConsumer Confidence Report Inadequate Reporting · code 72 | Consumer Confidence Rulecode 7000 | No | Unaddressed |
| 2025-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitratecode 1040 | No | Archived |
| 2024-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | Endothallcode 2033 | No | Archived |
| 2024-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | 1,2-Dibromo-3-chloropropane (DBCP)code 2931 | No | Archived |
| 2024-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | Benzo(a)pyrenecode 2306 | No | Archived |
| 2024-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | Di(2-ethylhexyl) phthalatecode 2039 | No | Archived |
| 2024-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | Dinosebcode 2041 | No | Archived |
| 2024-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | Di(2-ethylhexyl) adipatecode 2035 | No | Archived |
| 2024-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | Heptachlor epoxidecode 2067 | No | Archived |
| 2024-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | Carbofurancode 2046 | No | Archived |
| 2024-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | 2,4-Dcode 2105 | No | Archived |
| 2024-04-01 | Monitoring and reportingMonitoring, Regular · code 03 | Glyphosatecode 2034 | No | Archived |
The 12 most recent violations in EPA's records, newest first.Labels and codes come from EPA's SDWIS reference tables. A monitoring or reporting violation means a required test or report was missed or late; it does not by itself mean a contaminant was found. "Health-based" marks violations of a legal limit or required treatment.
Siasconset Water Department: frequently asked questions
Who runs Siasconset Water Department?
Siasconset Water Department (PWSID MA4197001) is a community water system owned by a local government. It is regulated by the MA state drinking water program.
How many people does Siasconset Water Department serve?
Siasconset Water Department reports serving 3,000 people through 863 service connections in Nantucket County, Massachusetts.
Where does Siasconset Water Department get its water?
EPA SDWIS lists this system's primary water source as groundwater. Groundwater means the system draws its water from wells or springs fed by underground aquifers.
Does Siasconset Water Department have any drinking water violations?
Of the 12 most recent violations in EPA's records, none is health-based, and the most recent began in July 2025. A monitoring or reporting violation means a required test or report was missed or late; it does not by itself mean a contaminant was found.
Is Siasconset Water Department's water safe to drink?
AquaCensus shows EPA compliance records, not current water test results, so it cannot say whether the water is safe at a given moment. Of the 12 most recent violations in EPA's records, none is health-based, and the most recent began in July 2025. For current results, consult the system's annual water quality report, EPA ECHO, or the MA state drinking water program.
Where can I find Siasconset Water Department's water quality report?
As a community water system, Siasconset Water Department must deliver an annual water quality report, called a Consumer Confidence Report, to its customers by July 1 each year, covering the previous calendar year. The system can provide a copy on request.
Other water systems in Nantucket County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Wannacomet Water Company | Nantucket | 27,703 | Community | Groundwater |
| Surfside Beach | Nantucket | 1,500 | Transient non-community | Groundwater |
| Wauwinet House | Nantucket | 300 | Transient non-community | Groundwater |
| Sankaty Head Golf Club Inc.. | Nantucket | 60 | Transient non-community | Groundwater |
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About this data
Source: U.S. EPA Safe Drinking Water Information System (SDWIS) and SDWA violation records, via EPA ECHO, as published October 1, 2026 — AquaCensus refreshes it quarterly. See the methodology for how records are matched, cleaned and scored.
Cite as: AquaCensus, “Siasconset Water Department, PWSID MA4197001, Massachusetts”, https://aquacensus.com/water-systems/massachusetts/siasconset-water-department-ma4197001 (data as of October 1, 2026).