Public water system · WA5369750

Active

Prosser City of

At a glance

City of Prosser (PWSID WA5369750) is an active community water system in Benton County, Washington. It reports serving 12,070 people through 2,889 service connections. Its primary water source is groundwater, and EPA lists it as owned by a local government. EPA's records list 11 violations for this system; 2 are health-based, and the most recent began in January 2023.

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

Population served

12,070

Service connections

2,889

Primary source

Groundwater

System type

CWS

Community water system

System record

PWSIDWA5369750

System typeCommunity water system

Activity statusActive

Population served12,070

Service connections2,889

Primary water sourceGroundwater

Owner typeLocal government

Primacy agencyWA state drinking water program

City served—

StateWashington

ZIP—

CountyBenton County

How does City of Prosser compare with other water systems in Benton County?

By EPA's size categories, City of Prosser is a large system (10,001 to 100,000 people). Benton County has 108 active public water systems, and City of Prosser is the 4th-largest of them by population served. Its population served is about 4.5 times the county average of 2,712 people per system, and accounts for 4.1% of the 292,896 people reported by systems filed under the county. Across Washington, the 4,705 active systems average 2,172 people each. Nationally, the average active community water system reports serving 6,703 people, so City of Prosser is about 80% 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. Washington has 2,392 active community water systems, 51% of the state's 4,705 active systems. Groundwater means the system draws its water from wells or springs fed by underground aquifers. 4,370 Washington systems (93%) list groundwater as their primary source.

Who owns and regulates City of Prosser?

EPA lists City of Prosser as owned by a local government. The WA state drinking water program is its primacy agency, the regulator with primary enforcement responsibility for the system under the Safe Drinking Water Act. 13 of the 108 active systems in Benton County (12%) are also owned by a local government.

Does City of Prosser have drinking water violations?

EPA's records list 11 violations for this system; 2 are health-based, and the most recent began in January 2023. The violations listed here began between October 1979 and January 2023. By type: 8 monitoring and reporting, 2 contaminant level above the legal limit and 1 public notice, recordkeeping or other. The contaminant or rule involved most often is Total coliform bacteria (TCR) (4 of them). EPA lists 6 as resolved and 5 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
2023-01-01	Monitoring and reportingMonitoring, Regular · code 03	Nitratecode 1040	No	Resolved
2014-07-01	Public notice, recordkeeping or otherConsumer Confidence Report Complete Failure to Report · code 71	Consumer Confidence Rulecode 7000	No	Resolved
2014-01-01	Monitoring and reportingFollow-up Or Routine LCR Tap M/R · code 52	Lead and Copper Rulecode 5000	No	Resolved
2010-01-01	Monitoring and reportingFollow-up Or Routine LCR Tap M/R · code 52	Lead and Copper Rulecode 5000	No	Resolved
2008-07-01	Monitoring and reportingMonitoring, Regular · code 03	Fluoridecode 1025	No	Resolved
2004-10-01	Monitoring and reportingMonitoring, Regular · code 03	Fluoridecode 1025	No	Resolved
1996-10-01	Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22	Total coliform bacteria (TCR)code 3100	Yes	Archived
1994-10-19	Monitoring and reportingMonitoring, Routine Major (TCR) · code 23	Total coliform bacteria (TCR)code 3100	No	Archived
1994-01-01	Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22	Total coliform bacteria (TCR)code 3100	Yes	Archived
1992-09-01	Monitoring and reportingMonitoring, Routine Minor (TCR) · code 24	Total coliform bacteria (TCR)code 3100	No	Archived
1979-10-01	Monitoring and reportingMonitoring, Regular · code 03	Gross alpha (excluding radon and uranium)code 4000	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 Prosser: frequently asked questions

Who runs City of Prosser?

City of Prosser (PWSID WA5369750) is a community water system owned by a local government. It is regulated by the WA state drinking water program.

How many people does City of Prosser serve?

City of Prosser reports serving 12,070 people through 2,889 service connections in Benton County, Washington.

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

EPA's records list 11 violations for this system; 2 are health-based, and the most recent began in January 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 Prosser'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; 2 are health-based, and the most recent began in January 2023. For current results, consult the system's annual water quality report, EPA ECHO, or the WA state drinking water program.

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

As a community water system, City of Prosser 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 Benton County

Water system	County	Population served	Type	Source
Kennewick City of	Benton	118,164	Community	Surface water
Richland City of	Benton	106,499	Community	Surface water
West Richland City of	Benton	21,231	Community	Purchased surface water
Energy Dept of/200w	Benton	6,351	Non-transient non-community	Surface water
Benton City Water	Benton	5,626	Community	Groundwater
Badger Mountain Irrigation District	Benton	2,331	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, “Prosser City of, PWSID WA5369750, Washington”, https://aquacensus.com/water-systems/washington/prosser-city-of-wa5369750 (data as of October 1, 2026).