Do they really have to drain the whole reservoir?

Did you read about the kid who peed in the reservoir that supplies drinking water to Portland? First of all, he denied that any of his pee reached the reservoir. He said he peed on a wall. Here is a photo from the security tape of him doing his deed.


So, Portland has decided to drain the entire 38 million gallon reservoir! the kid says he sees dead animals in the reservoir all the time. Casey Johnston writes,

A half-liter of urine dumped in a 143 million-liter reservoir would get a urea concentration of about 3 parts per billion, according to Slate. (We calculated it would be a 50 nanoMolar solution.) Meanwhile, the EPA allows concentrations of arsenic in drinking water up to 10 ppb. Salt water has a salt concentration of around 35,000,000 parts per billion, or 600 milliMolar.

Read more here.