From City of Milwaukie:
The city shut down its connection to the outside water supply as soon as it received the sampling results and began flushing the system.
Residents should not drink any water without boiling it first. Bring all water to a boil for at least one minute and cool before using. Using bottled water is encouraged. Boiled or bottled water should be used for drinking, making ice, brushing teeth, washing dishes and all food preparation until further notice. Ice or any beverages prepared with unboiled tap water on or after Nov. 9 should be discarded.
The results from a follow-up round of testing are expected back at noon on Friday, Nov. 11. The city will provide an update once these results are returned, as well as any further instructions, if needed.
Water contamination can occur for a number of reasons. The city is currently looking into the cause of the contamination and will provide updates as they are known.
E. coli can cause diarrhea, cramps, nausea, headaches, or other symptoms. It poses an increased health risk for infants, young children, and people with compromised immune systems. These symptoms are not caused by E. coli alone. If you experience any of these symptoms, consider seeking medical advice from your health care provider.
Source: http://www.milwaukieoregon.gov/citymanager/boil-water-notice-effect-milwaukie-water-customers