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Drinking Water Quality in Oregon

Most tap water in Oregon starts as a river, lake or reservoir. Enter your ZIP below to see which community water system EPA lists for your county, what the federal record shows for it, and where its official annual water quality report lives. Every number on this page is EPA's, from the April to June 2026 extract, and none of it is a safety verdict in either direction.

938 community water systems serve 3.7 million people in Oregon, 84 percent of them on surface water
Community water systems
938
People served, as reported
3.7 million
On surface water
84%
Counties with listed systems
36

Which water system serves your Oregon address?

EPA SDWA extract, April to June 2026

Oregon’s big cities drink protected mountain watersheds, Portland from the Bull Run and much of the valley from the Cascades, which puts 84 percent of the reported served population on surface water. Its 938 community systems include hundreds of small coastal and mountain districts, and primacy sits with the health authority rather than an environmental agency.

County by county

Oregon water systems by County

EPA's federal file lists active community water systems in 36 counties of Oregon. The table below is that record, sorted by reported population served. It is an inventory, not a ranking: a county with more listed violations is often just a county whose systems and state program report more completely.

Loading the county table from the committed EPA snapshot…

A small town water tower on steel legs against a clear sky
The water tower is the visible tip of a community water system, and most of the systems in the table above are this size: a town, a district or a cooperative serving a few hundred to a few thousand people. Small systems carry most of the listed violations nationally, largely because staying on top of every sampling schedule is hardest with one part time operator. “Seelyville-Town-Hall-water-tower-in” by Brian Stansberry, CC BY 4.0
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Where it comes from

Oregon mostly drinks treated surface water

By reported population served, 84 percent of community system customers in Oregon are on surface water and 16 percent on ground water. That clears the 75 percent surface supermajority only 22 states reach, and it shapes everything: surface water must be filtered and disinfected continuously, so the state's water quality story is a treatment plant story. 103 of the state's systems buy some or all of their water wholesale from another system, so the system on your bill is not always the system running the treatment plant.

938
Community systems
rank 19 of 50 by count
666,200
Largest system, people served
Portland Water Bureau
103
Systems buying water wholesale
purchased ground or surface water
3
Systems with nothing listed
no reported violations, which is not a clean bill

Portland Water Bureau

666,200

people served, on surface water, serving Multnomah county. PWSID OR4100657.

EPA listed inventory

Tualatin Valley Water District

224,600

people served, on purchased surface water, serving Washington county. PWSID OR4100665.

EPA listed inventory

Salem Public Works

199,820

people served, on surface water, serving Marion county. PWSID OR4100731.

EPA listed inventory

Eugene Water & Electric Board

176,000

people served, on surface water, serving Lane county. PWSID OR4100287.

EPA listed inventory

Population served is self reported by each system to its regulator, and a wholesaler and the systems buying from it can both count the same household. Summed across Oregon that overlap inflates the total, so read the 3.7 million figure as the sum of what systems report, not as a census of people.

Our summary of information published by EPA SDWA quarterly download (SDWIS federal data)

What EPA lists, in EPA's categories

Violations in the federal record for Oregon

As of the April to June 2026 extract, EPA's files list at least one health based violation that began in the five years to 2026-06-30 for 231 of Oregon's 938 community systems, which is 24.6 percent. 250 systems currently carry a violation EPA's status field marks Unaddressed. Health based is EPA's own dividing line, and it matters more than any total:

“These violations fall into three categories: Exceedances of the maximum contaminant levels (MCLs), which specify the highest allowable contaminant concentrations in drinking water; Exceedances of the maximum residual disinfectant levels (MRDLs), which specify the highest concentrations of disinfectants allowed in drinking water; and Treatment technique requirements, which specify certain processes intended to reduce the level of a contaminant.”

US EPA ECHO, SDWA Data Download Summary (health based violations)

Everything else in the record is mostly monitoring and reporting: a required test or report that did not happen on schedule. Those are the bulk of all listed violations nationally, and they say nothing about what was in the water, only that nobody checked when the rules said to. Two more of EPA's own definitions worth knowing when you read a system's record: a violation is Unaddressed when, in EPA's words, "The violation is not Resolved or Archived, and has not been addressed by formal enforcement." and Archived when it is more than five years past its end date.

“The violation is not Resolved, but is more than five years past its noncompliance period end date. In keeping with the Enforcement Response Policy, the violation no longer contributes to the public water system’s overall compliance status.”

US EPA ECHO, SDWA Data Download Summary (violation status: Archived)

And the caveat that binds this whole page, in the agency's words rather than ours:

“Compliance statistics are based on violations reported by states to the EPA Safe Drinking Water Information System (SDWIS). EPA is aware of inaccuracies and underreporting of some data in this system. We are working with the states to improve the quality of the data.”

US EPA ECHO, Drinking Water (SDWA) FAQs

“Due to the known incompleteness of the data reported by states and regions, we are careful to refer to systems as having reported violations or no reported violations.”

US EPA ECHO, Drinking Water (SDWA) FAQs

This is why Oregon's percentages cannot be compared against another state's as if they measured the water. A state whose program reports quickly and completely will show more listed violations than one that lags, for the same pipes and the same rivers. We publish EPA's counts with EPA's caveats and rank nobody.

Our summary of information published by EPA ECHO Drinking Water FAQs

Concrete sedimentation and clarifier basins full of water at a drinking water treatment plant
Sedimentation and clarifier basins at a drinking water treatment plant, in an EPA photograph. Every system on this page treating a river or reservoir runs some version of this, continuously, which is what a treatment technique violation is about: not a bad sample but a required process falling short. “The coagulation and filtration processes at a drinking water treatment plant. (14868618507)” — US Environmental Protection Agency — Public domain
The official record

Where Oregon's real water quality answers live

This page shows the compliance record. The actual test results, what was measured in the water and at what concentration, live in each system's annual Consumer Confidence Report, and federal law puts one in your hands every year:

“EPA requires community water systems to deliver a Consumer Confidence Report, also known as an annual drinking water quality report, to their customers. These reports provide Americans information about their local drinking water quality.”

US EPA, CCR Information for Consumers

“Reports must be sent by your water supplier each year by July 1.”

US EPA, CCR Information for Consumers

Find yours through EPA Consumer Confidence Report search or on your utility's website. Day to day regulation belongs to Oregon Health Authority, Drinking Water Services, the state's primacy agency, whose records for any single system run deeper and fresher than the federal extract this page reads. Health questions about your tap water belong to your water system, your county health department and CDC Drinking Water, not to this page.

If you are on a private well, none of the above applies to you, and that is worth saying plainly:

“The quality and safety of drinking water from private domestic wells are not regulated by the Federal Government under the Safe Drinking Water Act nor by most state governments and laws.”

US EPA, Private Drinking Water Wells

Testing a private well is the owner's job. Oregon Health Authority, Drinking Water Services and county health departments publish what to test for locally, and EPA's private wells pages cover the basics.

Common questions

Oregon drinking water FAQ

Keep going

The rest of Oregon's water picture

Drinking water in nearby states

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Inventory and violation counts are EPA's, from the April to June 2026 SDWA quarterly extract (published July 2026), active community water systems only. ZIP to county resolution uses the Census Bureau's ZCTA relationship file. Live checks read EPA Envirofacts. All are US Government works in the public domain. National picture: drinking water in every state