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Human Health & Well Water

Contaminants in Well Water

While many wells in Oregon provide clean water for many people, some wells do become contaminated due to natural and un-natural causes. This contamination can cause both short and long-term health effects.


The best way to know if your well water is safe is to get it tested!

How to get your water tested

What contaminants can be present in well water?

Both natural and un-natural contaminants can make their way into your water supply. Natural chemical or mineral contaminants may include arsenic and radon, while un-natural contaminants such as pesticides, chemicals, and bacteria can also be found in your water as a result of land use practices, storm water overflow, and other events happening near your well. Contaminants vary by location and all wells, despite a neighbor's lack of contaminants or varying well depth, should be routinely monitored to ensure your and your family's good health.

In Oregon, routine testing for PDF iconnitrate, PDF iconcoliform bacteria, and PDF iconarsenic is recommended. If selling a property in Oregon, these tests are required by law.

Can these contaminants make me and others sick?

The short answer to this question is yes. While it may depend on the toxicity of a chemical, its concentration, and the duration of exposure, well water contaminants can lead to short and or long term health effects. The Centers for Disease Control and Prevention (CDC) have identified the following to be the most common outbreaks in domestic well systems:  

  • Hepatitis A (liver disease usually spread by ingesting fecal matter)
  • Giardia intestinalis (diarrheal disease caused by feces contamination)
  • Campylobacter (infectious disease caused by bacteria)
  • E. coli (bacteria caused disease)
  • Shigella (infectious disease caused by a group of bacteria)
  • Salmonella (infectious disease caused by a group of bacteria)
  • Cryptosporidium (diarrheal disease caused by parasite)
  • Arsenic and Nitrate poisoning (cancer and other symptoms)
  • NEW! Harmful Algae Blooms English / Spanish (produce toxins, and when ingested can cause negative health effects)

While everyone in your household may not be affected, vulnerable populations (i.e.: children, the elderly, pregnant women, and autoimmune compromised individuals) are particularly susceptible. For other contaminants and their health effects, visit Drinking Water Services' list of chemicals.  

How do I know if there are contaminants in my well?

Your well should be tested once a year by an accredited laboratory to monitor any contaminants present in your water supply. Several contaminants can be tested and what you choose to test for may depend on where your well is located on your property and whether you live in an urban or rural area.

To help prevent contamination, visit our construction, testing, and resource section for more information. The National Groundwater Association also provides helpful tips on how to prevent contamination

What should I do if there are contaminants in my well?

If you suspect your water may be contaminated, you should have your water tested. It is recommended that you test for nitrates and bacteria every year. Arsenic testing can be done once or every 3-5 years dependent on water quality. While you wait for results, if you suspect contamination it is recommended that you drink potable water from another source until notified of your results. Information on testing, how to read results, and treatment is available.

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