Comic #127 : "Demarcation"

So, if you hadn't heard, Portland decided to dump all of the water from a 38 million gallon reservoir because a teenager peed in it. Now, as an open air reservoir, this means birds will defecate in it daily, trash will get blown in it, it's exposed to air pollution - so in the grand scheme of things a little pee makes no difference even if it could be detectable in 38 million gallons worth of water.