In my Environmental Engineering class we learned that in the USA, unlike much of the rest of the world, water is chlorinated during the treatment process. The r

In my Environmental Engineering class we learned that in the USA, unlike much of the rest of the world, water is chlorinated during the treatment process. The residual chlorine left in the water makes tap water less susceptible to contamination than other treatment methods. A quick google search indicates tap water in Portland is in fact chlorinated (actually, chloramined, which is even safer but has similar benefits), so a small amount of pathogens shouldn't make the water undrinkable.