Public water system · OR4100665
ActiveTualatin Valley Water District
At a glance
Tualatin Valley Water District (PWSID OR4100665) is an active community water system in Washington County, Oregon. It reports serving 224,600 people through 62,160 service connections. Its primary water source is purchased surface water, and EPA lists it as owned by a local government. EPA's records list 2 violations for this system; none is health-based, and the most recent began in January 2025.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
224,600
Service connections
62,160
Primary source
SWP
Purchased surface water
System type
CWS
Community water system
System record
How does Tualatin Valley Water District compare with other water systems in Washington County?
By EPA's size categories, Tualatin Valley Water District is a very large system (more than 100,000 people). Washington County has 97 active public water systems, and Tualatin Valley Water District is the largest of them by population served. Its population served is about 36 times the county average of 6,158 people per system, and accounts for 38% of the 597,296 people reported by systems filed under the county. Across Oregon, the 2,536 active systems average 1,587 people each. Nationally, the average active community water system reports serving 6,703 people, so Tualatin Valley Water District is about 34 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. Oregon has 940 active community water systems, 37% of the state's 2,536 active systems. Purchased surface water means the system buys surface water from another public water system rather than drawing its own. 105 Oregon systems (4.1%) list purchased surface water as their primary source.
Who owns and regulates Tualatin Valley Water District?
EPA lists Tualatin Valley Water District as owned by a local government. The OR state drinking water program is its primacy agency, the regulator with primary enforcement responsibility for the system under the Safe Drinking Water Act. 26 of the 97 active systems in Washington County (27%) are also owned by a local government.
Does Tualatin Valley Water District have drinking water violations?
EPA's records list 2 violations for this system; none is health-based, and the most recent began in January 2025. The violations listed here began between April 2001 and January 2025. By type: 2 monitoring and reporting. The contaminants or rules involved are Nitrate and Total coliform bacteria (TCR). EPA lists 1 as archived and 1 as resolved. 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. 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 |
|---|---|---|---|---|
| 2025-01-01 | Monitoring and reportingMonitoring, Regular · code 03 | Nitratecode 1040 | No | Archived |
| 2001-04-01 | Monitoring and reportingMonitoring, Routine Minor (TCR) · code 24 | Total coliform bacteria (TCR)code 3100 | No | Resolved |
All 2 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.
Tualatin Valley Water District: frequently asked questions
Who runs Tualatin Valley Water District?
Tualatin Valley Water District (PWSID OR4100665) is a community water system owned by a local government. It is regulated by the OR state drinking water program.
How many people does Tualatin Valley Water District serve?
Tualatin Valley Water District reports serving 224,600 people through 62,160 service connections in Washington County, Oregon.
Where does Tualatin Valley Water District get its water?
EPA SDWIS lists this system's primary water source as purchased surface water. Purchased surface water means the system buys surface water from another public water system rather than drawing its own.
Does Tualatin Valley Water District have any drinking water violations?
EPA's records list 2 violations for this system; none is health-based, and the most recent began in January 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 Tualatin Valley Water District'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 2 violations for this system; none is health-based, and the most recent began in January 2025. For current results, consult the system's annual water quality report, EPA ECHO, or the OR state drinking water program.
Where can I find Tualatin Valley Water District's water quality report?
As a community water system, Tualatin Valley Water District 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 Washington County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Hillsboro, City of | Washington | 92,632 | Community | Purchased surface water |
| Beaverton, City of | Washington | 88,045 | Community | Purchased surface water |
| Tigard, City of | Washington | 62,500 | Community | Purchased surface water |
| Tualatin, City of | Washington | 28,106 | Community | Purchased surface water |
| Forest Grove, City of | Washington | 26,838 | Community | Surface water |
| Sherwood, City of | Washington | 19,885 | 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, “Tualatin Valley Water District, PWSID OR4100665, Oregon”, https://aquacensus.com/water-systems/oregon/tualatin-valley-water-district-or4100665 (data as of October 1, 2026).