Oregon Private Well Water Quality 2026

PFAS in Oregon Well Water

Oregon has 35 public water systems with confirmed PFAS detections, of which 24 exceed the EPA’s new federal drinking water standards — according to the Oregon Health Authority’s own testing data as of 2025. But public water systems, whatever their problems, at least face monitoring requirements. Private well owners in Oregon have no equivalent protection and no obligation to test for PFAS at any point other than property sale, and even then, PFAS is not on the mandatory sale-transaction test list.

A 2024 US Geological Survey study estimated that around 800,000 Oregonians — from both public and private wells — may rely on groundwater that could be contaminated with PFAS, ranking Oregon 25th nationally for the number of people potentially affected. The USGS study, which modelled predicted contamination across the country, found that detections cluster along the Interstate 5 corridor, where population and industrial density are highest.

The primary PFAS contamination sources in Oregon are consistent with the national picture: commercial airports required to maintain PFAS-containing AFFF firefighting foam, military bases, municipal fire training facilities near major cities, industrial sites, landfills, and the spreading of biosolids (sewage sludge containing PFAS) on agricultural land in eastern Oregon. The Oregon DEQ identified eight commercial airports and 18 municipal fire training facilities near 20 of the state’s most populous cities as suspected PFAS sources in 2025 rulemaking documents.

Hermiston — eastern Oregon’s largest city — is one of the clearest examples of the scale of the problem. Hermiston’s municipal water tested above the federal maximum contaminant level for PFOS in both 2023 and 2024, and additional PFAS chemicals were detected in its water supply. The contamination source has not been identified. The city has taken a “wait-and-see” approach to further testing and remediation — a position that illustrates the regulatory gap between confirmed contamination and action. Well owners on private systems near Hermiston have no equivalent monitoring at all.

Arsenic in Oregon Well Water

Arsenic is a documented, geologically sourced threat to well owners across Oregon. Oregon’s real estate transaction (RET) testing programme — which collects well water test results at property sale — has received over 3,300 arsenic results, of which approximately 9.7% exceed the federal MCL of 10 parts per billion. A further 2% were classified as “very high.” These figures understate the true picture, since testing only occurs at sale and many well-served households have never had their arsenic levels assessed.

Arsenic hotspots in Oregon are concentrated in specific geological zones. The area around Sweet Home in Linn County has some of the most elevated readings in the state, with approximately 25% of wells in the area exceeding EPA limits — a figure derived from USGS groundwater studies and corroborated by Linn County’s own health department data. The Tualatin Basin in the northwest metro area is another documented hotspot. Parts of Lane County (particularly around Cottage Grove), Jackson County, and Eastern Oregon’s high-desert aquifers also carry elevated arsenic risk.

The Willamette Basin geology — primarily Columbia River Basalt and alluvial sediments — releases arsenic naturally as groundwater moves through the rock. Arsenic is colourless and tasteless; there is no way to detect it without laboratory testing. Long-term exposure is linked to bladder, lung and skin cancers, cardiovascular disease, and neurological damage.

Nitrate and Bacteria Risks

Nitrate contamination from agricultural fertiliser runoff, animal feedlot operations and failing septic systems is a persistent problem in Oregon’s well water, particularly in the three Groundwater Management Areas (GWMAs) that the Oregon DEQ has formally declared due to nitrate exceeding trigger levels. Oregon’s RET database — built from well tests submitted at property sale since 1989 — has recorded over 25,000 nitrate results, of which approximately 1.7% exceeded the federal drinking water limit of 10 mg/L. That figure closely mirrors the 2004 DEQ analysis and is consistent across multiple reviews of the dataset.

The Lower Umatilla Basin Groundwater Management Area in northern Morrow and northwestern Umatilla counties is the most severely affected area in Oregon. The OHA has been actively providing free nitrate testing, water treatment systems and emergency bottled water deliveries to households in this area — a programme that remains ongoing as of 2025. High nitrate levels (at or above 10 mg/L) are especially dangerous for infants under six months, and pregnant people are also in a higher-risk group.

Coliform bacteria — including E. coli — appear in approximately 12% of Oregon well water samples in the RET database, making bacterial contamination one of the most common well water failures in the state. Risk factors include older or poorly sealed wells, proximity to septic systems, flooding events, and nearby livestock operations.

Regulatory Situation for Oregon Well Owners

Private residential wells in Oregon are not regulated under the federal Safe Drinking Water Act, and neither OHA nor DEQ tests or pays for private well testing. Oregon law does require testing at property sale — for arsenic, nitrate and total coliform bacteria only — and results must be submitted to OHA and provided to the buyer within 90 days. PFAS is not included in this mandatory test. Beyond property sale, testing and treatment of a private well is entirely the responsibility of the well owner.

For PFAS in public water systems, Oregon’s state deadline to adopt the federal EPA standards was April 2026. Public water systems were originally required to achieve compliance by April 2029; however, in May 2025 the Trump EPA announced its intent to extend this deadline to 2031 for PFOA and PFOS, and to rescind the separate MCLs for four other PFAS compounds (PFHxS, PFNA, HFPO-DA/GenX, and the hazard index mixture). A proposed rule to formalise this extension was expected in autumn 2025, with finalisation planned for spring 2026 — though the regulatory position remains in flux. None of these rules apply to private wells under any timeline. Oregon DEQ is separately in the process of rulemaking to add six PFAS compounds to the state’s list of regulated hazardous substances — the first update to that list since 2006 — but the regulatory focus is on soil, groundwater and surface water cleanup at known pollution sites, not on private well monitoring.

Check our Oregon municipal water quality page for city-by-city tap water data, including Portland, Salem and Eugene. You can also use our live boil water notice tracker for active advisories across the state.

Known High-Risk Areas in Oregon

If you live near any of the following locations, well water testing is urgent — not precautionary.

How to Test Your Oregon Well Water — and What to Do Next

Oregon has more infrastructure around private well guidance than many states — the OHA Domestic Well Safety Programme, DEQ oversight of contamination cases, and the OSU Well Water Programme all provide useful resources. But infrastructure is not the same as protection: none of these agencies are funded to test your well for you, and PFAS testing is not part of any mandatory programme for private well owners. The OHA and DEQ both recommend testing every one to two years.

To find a certified laboratory, contact the OHA Domestic Well Safety Programme at 971-673-0977 or use OHA’s accredited lab list online. If you’re in the Lower Umatilla Basin, contact OHA directly to ask about free nitrate testing and treatment under the active assistance programme. For PFAS, use a lab accredited by the Oregon Environmental Laboratory Accreditation Program (ORELAP) analysing samples using EPA method 533 or 537.1.

For filter options, our well water filter guide covers reverse osmosis systems for PFAS and arsenic, UV disinfection for bacteria, and whole-house well systems for comprehensive treatment. You can also browse our full water filter solutions page or check your ZIP code for local water quality context.

For other West Coast and Pacific Northwest well water risks, see our pages on Ohio wells and Michigan wells. Return to the private well water directory to find your state.