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Well Testing & Regulations

Domestic Well Testing

Yearly testing is recommended for private wells.

Testing is required during a real estate transaction. 

What is domestic well testing and when should I test my water?

Domestic well testing is the process of having an accredited laboratory test water from a private well for possible contaminants, with the most common being arsenic, nitrate, and total coliform bacteria. You can also test for other contaminants. To determine what other contaminants you may be at risk for, call your local health department.

Testing is required by law if selling a property with a private well, and recommended yearly if using a well as source of potable water.

Find an Accredited Laboratory

What are my legal responsibilities if I plan to sell my property? What is the Real Estate Transaction (RET) Law?

ORS 448.271 requires testing of domestic well water during a real estate transaction. The Oregon Real Estate Transaction law states:

"In any transaction for the sale or exchange of real estate that includes a well that supplies ground water for domestic purposes, the seller of the real estate shall, upon accepting an offer to purchase that real estate, have the well tested for arsenic, nitrates and total coliform bacteria. The Oregon Health Authority also may, by rule, require additional tests for specific contaminants in specific areas of public health concern. The seller shall submit the results of the tests required under this section to the authority and to the buyer within 90 days of receiving the results of the tests."

See below for information about reporting your results. Oregon Administrative Rules 333-061-0305 to 333-061-0335 further define the actions you must take if you are selling your home or property.  

Who needs to comply with the Real Estate Transaction Law testing regulations?

The seller of the real estate, or property, is responsible. However, the seller can designate their attorney, real estate agent or broker, laboratory person conducting the water testing, or a private party to assist them in complying with water testing and reporting requirements. The potential buyer must be notified of the results within 90 days and results should be sent to the state of Oregon's Drinking Water Services. The test results are valid for one year.

How do I test my water?

To test your water, you must take a water sample.

  • Use the water collection kit supplied by the laboratory. Most will provide detailed instructions. If they don't, refer to the guidance below on collecting a water sample.
  • Get the sample to the lab as soon as possible, within 24 hours of collection.
  • The sample must be taken correctly in order to show the most accurate results.
  • Test results are usually ready one to three business days after the lab receives the samples. Some tests (like arsenic) may take up to 10 business days or longer dependent on analysis type.
Collecting a Water Sample  Find an Accredited Laboratory

What should I test my water for and how much will it cost?

In Oregon, it is recommended that you test for bacteria and nitrate every year. If these are present, it most likely means that surface contamination has found its way into the well and disease causing organisms may be in your water.

In addition, testing for arsenic should be done at least once to see if arsenic is present and at what levels. Some areas in Oregon are particularly susceptible and certain counties are encouraged to routinely check their wells' arsenic levels. If arsenic is present in an initial test (above 8ppb), you should retest. Upon the retest, if high concentrations continue, a treatment system should be installed. With a treatment system, testing should be done each year at point of use and every three years at the well head.

Testing for the most common risks will typically cost from $20 to $40 for nitrate analysis, $25 to $40 for coliform bacteria (microbiological) testing, and $20 to $45 for arsenic analysis. If other contaminants are suspected, more extensive testing may be warranted. Make sure to use an accredited laboratory.

Do I need to report my results? Where should I send them?

If you are just routinely testing your well, there is no obligation to report your results. 

If you are selling your property, you must report specific information about the well and the quality of the water within 90 days from receiving the results to both the potential buyer and the state of Oregon (ORS 448.271).

To make sure all necessary information is provided, the seller should complete a PDF iconDomestic Well Testing For Real Estate Transaction form. Blank forms are also available from local real estate offices and Oregon Drinking Water Services. The completed Domestic Well Testing For Real Estate Transaction form and laboratory test results should be sent to:

    Domestic Well Safety Program (DWSP)
    800 NE Oregon Street,Suite 640
    Portland, OR 97232

What if the well water does not meet safe standards?

Technical assistance is available to you.

Contact your local health department for more information or visit our Treatment and Maintenance page and Other Resources page.

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