Public water system · MI0004170

Active

Mason, City of

At a glance

City of Mason (PWSID MI0004170) is an active community water system in Ingham County, Michigan. It reports serving 8,252 people through 3,200 service connections. Its primary water source is groundwater, and EPA lists it as owned by a local government. EPA's records list 10 violations for this system; 3 are health-based, and the most recent began in July 2023.

Dataset updated October 2026 . Source: EPA SDWIS/ECHO public records.

Population served

8,252

Service connections

3,200

Primary source

Groundwater

System type

CWS

Community water system

System record

PWSIDMI0004170

System typeCommunity water system

Activity statusActive

Population served8,252

Service connections3,200

Primary water sourceGroundwater

Owner typeLocal government

Primacy agencyMI state drinking water program

City servedMason

StateMichigan

ZIP—

CountyIngham County

How does City of Mason compare with other water systems in Ingham County?

By EPA's size categories, City of Mason is a medium system (3,301 to 10,000 people). Ingham County has 108 active public water systems, and City of Mason is the 5th-largest of them by population served. Its population served is about 3.2 times the county average of 2,577 people per system, and accounts for 3% of the 278,352 people reported by systems filed under the county. Across Michigan, the 10,599 active systems average 847 people each. Nationally, the average active community water system reports serving 6,703 people, so City of Mason is about 23% above 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. Michigan has 1,332 active community water systems, 13% of the state's 10,599 active systems. Groundwater means the system draws its water from wells or springs fed by underground aquifers. 10,214 Michigan systems (96%) list groundwater as their primary source.

Who owns and regulates City of Mason?

EPA lists City of Mason as owned by a local government. The MI state drinking water program is its primacy agency, the regulator with primary enforcement responsibility for the system under the Safe Drinking Water Act. 12 of the 108 active systems in Ingham County (11%) are also owned by a local government.

Does City of Mason have drinking water violations?

EPA's records list 10 violations for this system; 3 are health-based, and the most recent began in July 2023. The violations listed here began between August 1997 and July 2023. By type: 5 monitoring and reporting, 3 contaminant level above the legal limit and 2 public notice, recordkeeping or other. The contaminant or rule involved most often is Total coliform bacteria (TCR) (3 of them). EPA lists 10 as resolved. Resolved means at least one resolving action is on record: the system returned to compliance, the rule no longer applies, or no further action was needed.

Began	Violation	Contaminant or rule	Health-based	Status
2023-07-01	Public notice, recordkeeping or otherConsumer Confidence Report Inadequate Reporting · code 72	Consumer Confidence Rulecode 7000	No	Resolved
2023-01-01	Monitoring and reportingMonitoring and Reporting (DBP) · code 27	Haloacetic acids (HAA5)code 2456	No	Resolved
2023-01-01	Monitoring and reportingMonitoring and Reporting (DBP) · code 27	Total trihalomethanes (TTHM)code 2950	No	Resolved
2022-01-01	Monitoring and reportingMonitoring, Regular · code 03	Combined Radium (-226 and -228)code 4010	No	Resolved
2021-07-01	Public notice, recordkeeping or otherConsumer Confidence Report Complete Failure to Report · code 71	Consumer Confidence Rulecode 7000	No	Resolved
2005-01-04	Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02	Combined Radium (-226 and -228)code 4010	Yes	Resolved
2003-10-01	Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22	Total coliform bacteria (TCR)code 3100	Yes	Resolved
1999-01-01	Monitoring and reportingMonitoring, Regular · code 03	Gross alpha (excluding radon and uranium)code 4000	No	Resolved
1998-05-01	Monitoring and reportingMonitoring, Routine Minor (TCR) · code 24	Total coliform bacteria (TCR)code 3100	No	Resolved
1997-08-01	Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22	Total coliform bacteria (TCR)code 3100	Yes	Resolved

All 10 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.

City of Mason: frequently asked questions

Who runs City of Mason?

City of Mason (PWSID MI0004170) is a community water system owned by a local government. It is regulated by the MI state drinking water program.

How many people does City of Mason serve?

City of Mason reports serving 8,252 people through 3,200 service connections in Ingham County, Michigan.

Where does City of Mason 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 City of Mason have any drinking water violations?

EPA's records list 10 violations for this system; 3 are health-based, and the most recent began in July 2023. 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 City of Mason'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. EPA's records list 10 violations for this system; 3 are health-based, and the most recent began in July 2023. For current results, consult the system's annual water quality report, EPA ECHO, or the MI state drinking water program.

Where can I find City of Mason's water quality report?

As a community water system, City of Mason 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 Ingham County

Water system	County	Population served	Type	Source
Lansing Board of Water & Light	Ingham	166,000	Community	Groundwater
East Lansing, City of	Ingham	33,000	Community	Purchased groundwater
Meridian Township	Ingham	25,600	Community	Purchased groundwater
Michigan State University	Ingham	12,793	Community	Groundwater
Lansing Township	Ingham	5,500	Community	Groundwater
Williamston, City of	Ingham	3,917	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, “Mason, City of, PWSID MI0004170, Michigan”, https://aquacensus.com/water-systems/michigan/mason-city-of-mi0004170 (data as of October 1, 2026).