Arsenic in Well Water in Oregon

Real Estate Agent with Tomson Burnham, llc Licensed in the State of Oregon

ArsenicI was recently asked about arsenic streaks in my area. 

Arsenic is a natural element that occurs in soil and rocks.  Most people hear the word arsenic and immediately become concerned.  I work with a lot of buyers purchasing small acreage properties here in Salem, Oregon so am familiar with well testing.  In Oregon, the seller of a home with a well is required, by law, to test for coliform (e.coli) bacterias, as well as nitrates.  I advise my clients to ask for lead and arsenic at the same time.


The USGS (United States Geological Survey) compiles data from well testing from all over the United States.  Their sampling showed that there were some immediate concentrations of arsenic in the well water of the Willamette Basin.  Please do not read this sentence as there is arsenic in all well water in the Willamette Basin.  This is not the case.  Arsenic in Well Water in the USwell


There were some areas of high concentration of arsenic in the bedrock areas of Lane and Linn Counties, as well as some in the Tualatin Basin.  This is important for you to know as a buyer, so that you can do your due diligence and get your water tested. 


For more great information about arsenic in well water, check out the following websites:

Centers for Disease Control Arsenic Fact Sheet

NSF International Arsenic Fact Sheet

EPA Arsenic Fact Sheet


I am not a well expert or an expert on arsenic in well water.  If you are concerned about your water quality.  Talk with your local lab to find out about your water tested for arsenic.




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Comments (4)

Ki Gray
Austin, TX
Austin Real Estate
interesting.  I only thought of arsenic in industrial places.
Feb 19, 2008 05:33 PM
ARDELL DellaLoggia
Better Properties Seattle - Kirkland, WA
Can the water get arsenic later, if it tests well at time of purchase?  Does the amount of arsenic vary with the seasons?  Sorry to be ignorant on this, but I find it fascinating.
Feb 19, 2008 05:38 PM
Melina Tomson
Tomson Burnham, llc Licensed in the State of Oregon - Salem, OR
Principal Broker/Owner, M.S.


Yes you can have water test fine at sale and then develop it later.  As the water table changes so does the level of arsenic. It will change with the seasons as well.  You should have your well water tested every 6 months to one year out here.  Testing annually is VERY important.  You can develop e.coli bacteria as well.  Most owners fail to test their water regularly.  They tend to think they are only at risk if they are near an industrial plant.

Feb 19, 2008 05:45 PM
Kathy Judy
Tri-Cities Real Estate retired - Ontario, OR
I know a lot about arsenic.  My husband spent 13 years with a local Eco-Water franchise.  They did a lot of real estate water tests.  For you non Oregonians, our earnest money agreement states that the seller will have the water tested for coliform bacteria and nitrates if the domestic water is from a private well.  Until recently, many loan programs required this also.  Arsenic has come to notice recently because the federal government requires that there be 10 times less arsenic in city water than used to be allowed.  A little arsenic is ok and normal but too much is deadly.  Liver diseases are many times caused by arsenic.  The links in Melina's post will tell you a lot about it.  A reverse osmosis unit will take some arsenic out - sometimes there has to be an extra arsenic filter put on it.  Some loan programs are requiring arsenic tests.  It is naturally occuring in some areas much more than others.  As far as I know - arsenic wouldn't increase in water with the seasons- but I'm not sure that disturbance of the groundwater might not cause it to change.  There is a spot on Oregon's inspection addendum to have arsenic checked with the water check that is in the body of the em agreement.
Feb 19, 2008 06:01 PM