Oregon county well guide

Well Water in Multnomah County, OR: Testing, Contractors and Rules

About 12,277 households in Multnomah County, 4% of the county, rely on a private well. Nobody tests that water unless the owner does.

Labs within 40 milesLicensed contractors
4%of households on a private well
Share on wells, county vs state
Multnomah County4%
Oregon average16%
24licensed contractors serve the county
<1 mito the nearest certified lab, Rose City Laboratories
Yesstatewide test required when a home is sold

Wells are the exception in Multnomah County: about 12,277 households, under 4% of the county, are on a private well. Being in the minority means less local help, so this page gathers what applies.

Local rules for wells in Multnomah County

The rules that apply in Multnomah County are set at the state level in Oregon. The state does not require a test on a new well, and a test is required at sale. Some counties and townships add permits or setbacks of their own, so check locally before drilling. The state's own recommendations are below.

At a glance

Water test for a new wellNot required statewide

No statewide water test on a new well. The well must be built by an OWRD-licensed, bonded water supply well constructor (or by the landowner under a Landowner's Water Well Permit) to the OAR 690-210 standards, with a start card filed and the fee paid before drilling, a metal well ID tag attached, and a well report filed with OWRD within 30 days. Setbacks are 50 ft from a septic tank and 100 ft from a drainfield. Some counties ask for a bacteria test before a building permit is finaled, and lenders usually do.

Water test when a home is soldRequired

Yes. Oregon's Domestic Well Testing Act (ORS 448.271, OAR 333-061-0305 to 0335) requires the seller of a property with a domestic well to have the water tested by an ORELAP-accredited lab for arsenic, nitrate and total coliform bacteria, give the results to the buyer and report them to the Oregon Health Authority within 90 days of the sale. It is one of only a handful of state laws in the country that test private wells at transfer.

What the state recommends

The Oregon Health Authority recommends testing a domestic well every year for coliform bacteria and nitrate, and every three to five years for arsenic (found across the Willamette Valley, the Tualatin basin, Lane County and Klamath and Lake counties), plus pH, hardness, iron, manganese, lead and copper once. Add uranium and radon in Lane County and the Cascade foothills, and test again after flooding, well work or a change in taste, color or smell. In the Southern Willamette Valley and Lower Umatilla Basin Groundwater Management Areas, nitrate is the test that matters most.

Free or low-cost testingAvailable

No statewide free program. The OSU Extension Well Water Program runs free nitrate screening clinics around the state and publishes testing guidance, and Oregon Health Authority's Domestic Well Safety Program (971-673-0440) helps owners read results. The Lower Umatilla Basin (Morrow and Umatilla counties) has state-funded free nitrate testing and water delivery for affected wells. Otherwise the ORELAP labs below charge $30 to $60 for bacteria and nitrate and $150 to $250 for the real estate panel.

Getting your water tested near Multnomah County

The nearest certified lab is Rose City Laboratories in Portland, in the county, and it accepts samples from homeowners. There are 5 more within 40 miles, listed below with what each tests for.

5 certified labs within 40 miles

Licensed well contractors serving Multnomah County

Licensed help in Multnomah County includes All Seasons Well Drilling and Alpine Resources and 22 others. Every listing was matched to the Oregon license list; the "verify" link on each profile opens the state lookup.

Well depth and water chemistry

Well depth and water chemistry in Multnomah County follow the rock underneath it. Typical wells here run 160 to 420 feet; the median of 359 new domestic wells reported to OWRD since 2000 is 240 feet. Contaminants worth testing for in this part of Oregon include arsenic (naturally occurring across the willamette valley, the tualatin basin, lane county, the klamath and lake basins and parts of central oregon).

Typical well depth

160 to 420 feet; the median of 359 new domestic wells reported to OWRD since 2000 is 240 feet

Contaminants to test for
  • Arsenic (naturally occurring across the Willamette Valley
  • The Tualatin basin
  • Lane County
  • The Klamath and Lake basins and parts of central Oregon)
  • Nitrate (Southern Willamette Valley
  • Lower Umatilla Basin and Northern Malheur groundwater management areas
  • And shallow wells in farm country)
  • Coliform bacteria (statewide
  • Worst in shallow and older wells)
  • Iron and manganese (valley alluvium and coastal sands)
  • Hardness (basalt and limestone areas)
  • Uranium and radon (Lane County granite and Cascade foothills)
  • Hydrogen sulfide (deep basalt wells)
  • Sodium and boron (some Willamette Valley aquifers)
  • PFAS near airfields and industrial sites

Neighboring counties: Clackamas County, Washington County, Columbia County, Yamhill County.

What well work costs in Multnomah County

Basic bacteria and nitrate test$25 to $75lab fee, homeowner sample
Full panel lab test$150 to $400metals, VOCs, radiologicals
Well inspection$250 to $550flow, pressure, visual, water test
Submersible pump replacement$1,200 to $4,500parts and labor
Pressure tank replacement$400 to $1,200installed
Whole-house treatment system$800 to $6,000softener, iron filter, UV, RO
New well drilled$5,500 to $25,000about $25 to $65 per foot
Shock chlorination$80 to $300or about $20 as a DIY job

National ranges from published 2025 to 2026 contractor pricing. Local quotes vary with depth, access and materials.

Questions Multnomah County well owners ask

How many homes in Multnomah County are on a well?

About 12,277, or 4% of households, based on Census housing data and state well surveys. The share is highest outside the towns with public water.

Where is the closest certified lab to Multnomah County?

Rose City Laboratories in Portland, inside the county. It accepts homeowner samples.

Do I need a permit to drill a well in Multnomah County?

No statewide water test on a new well. The well must be built by an OWRD-licensed, bonded water supply well constructor (or by the landowner under a Landowner's Water Well Permit) to the OAR 690-210 standards, with a start card filed and the fee paid before drilling, a metal well ID tag attached, and a well report filed with OWRD within 30 days. Setbacks are 50 ft from a septic tank and 100 ft from a drainfield. Some counties ask for a bacteria test before a building permit is finaled, and lenders usually do.

What does a well test cost near Multnomah County?

A bacteria and nitrate test runs $25 to $75 at most certified labs; a full panel with metals is $150 to $400. Mail-in kits cost about the same as walking in.