Public water system · ND5301012

Active

Williston City of

At a glance

City of Williston (PWSID ND5301012) is an active community water system in Williams County, North Dakota. It reports serving 26,426 people through 6,876 service connections. Its primary water source is surface water, and EPA lists it as owned by a local government. EPA's records list 11 violations for this system; 8 are health-based, and the most recent began in November 2014.

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

Population served

26,426

Service connections

6,876

Primary source

Surface water

System type

CWS

Community water system

System record

PWSIDND5301012

System typeCommunity water system

Activity statusActive

Population served26,426

Service connections6,876

Primary water sourceSurface water

Owner typeLocal government

Primacy agencyND state drinking water program

City servedWilliston

StateNorth Dakota

ZIP—

CountyWilliams County

How does City of Williston compare with other water systems in Williams County?

By EPA's size categories, City of Williston is a large system (10,001 to 100,000 people). Williams County has 19 active public water systems, and City of Williston is the largest of them by population served. Its population served is about 13 times the county average of 1,990 people per system, and accounts for 70% of the 37,806 people reported by systems filed under the county. Across North Dakota, the 403 active systems average 1,864 people each. Nationally, the average active community water system reports serving 6,703 people, so City of Williston is about 3.9 times 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. North Dakota has 317 active community water systems, 79% of the state's 403 active systems. Surface water means the system draws its water from rivers, lakes, streams or reservoirs. 20 North Dakota systems (5%) list surface water as their primary source.

Who owns and regulates City of Williston?

EPA lists City of Williston as owned by a local government. The ND state drinking water program is its primacy agency, the regulator with primary enforcement responsibility for the system under the Safe Drinking Water Act. 8 of the 19 active systems in Williams County (42%) are also owned by a local government.

Does City of Williston have drinking water violations?

EPA's records list 11 violations for this system; 8 are health-based, and the most recent began in November 2014. The violations listed here began between July 1991 and November 2014. By type: 4 required treatment not met, 4 contaminant level above the legal limit and 3 monitoring and reporting. The contaminant or rule involved most often is Total trihalomethanes (TTHM) (4 of them). EPA lists 8 as resolved and 3 as archived. 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. 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.

Began	Violation	Contaminant or rule	Health-based	Status
2014-11-01	Monitoring and reportingMonitoring, Routine Minor (TCR) · code 24	Total coliform bacteria (TCR)code 3100	No	Resolved
2014-10-01	Monitoring and reportingMonitoring and Reporting (DBP) · code 27	Chloraminecode 1006	No	Resolved
2014-06-01	Required treatment not metTreatment Technique (SWTR and GWR) · code 41	Long Term 2 Enhanced Surface Water Treatment Rulecode 0800	Yes	Resolved
2011-02-01	Required treatment not metTreatment Technique (SWTR and GWR) · code 41	Long Term 2 Enhanced Surface Water Treatment Rulecode 0800	Yes	Resolved
2006-01-01	Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02	Total trihalomethanes (TTHM)code 2950	Yes	Resolved
2005-10-01	Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02	Total trihalomethanes (TTHM)code 2950	Yes	Resolved
2005-07-01	Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02	Total trihalomethanes (TTHM)code 2950	Yes	Resolved
1994-03-01	Required treatment not metTreatment Technique (SWTR and GWR) · code 41	Surface Water Treatment Rulecode 0200	Yes	Archived
1994-01-01	Contaminant level above the legal limitMaximum Contaminant Level Violation, Average · code 02	Total trihalomethanes (TTHM)code 2950	Yes	Resolved
1993-09-01	Required treatment not metTreatment Technique (SWTR and GWR) · code 41	Surface Water Treatment Rulecode 0200	Yes	Archived
1991-07-01	Monitoring and reportingMonitoring, Routine Minor (TCR) · code 24	Total coliform bacteria (TCR)code 3100	No	Archived

All 11 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 Williston: frequently asked questions

Who runs City of Williston?

City of Williston (PWSID ND5301012) is a community water system owned by a local government. It is regulated by the ND state drinking water program.

How many people does City of Williston serve?

City of Williston reports serving 26,426 people through 6,876 service connections in Williams County, North Dakota.

Where does City of Williston get its water?

EPA SDWIS lists this system's primary water source as surface water. Surface water means the system draws its water from rivers, lakes, streams or reservoirs.

Does City of Williston have any drinking water violations?

EPA's records list 11 violations for this system; 8 are health-based, and the most recent began in November 2014. 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 Williston'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 11 violations for this system; 8 are health-based, and the most recent began in November 2014. For current results, consult the system's annual water quality report, EPA ECHO, or the ND state drinking water program.

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

As a community water system, City of Williston 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 Williams County

Water system	County	Population served	Type	Source
Northwest Rural Water District	Williams	5,102	Community	Purchased surface water
Tioga City of	Williams	2,202	Community	Purchased surface water
R & T Water System	Williams	1,003	Community	Purchased surface water
Ray City of	Williams	950	Community	Purchased surface water
Trenton Water Users Assoc	Williams	840	Community	Purchased surface water
Inspire Communities-Springbrook	Williams	300	Community	Purchased surface water

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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, “Williston City of, PWSID ND5301012, North Dakota”, https://aquacensus.com/water-systems/north-dakota/williston-city-of-nd5301012 (data as of October 1, 2026).