Wee mathematics in Portland, Oregon

Today’s mathematics exercise: What, approximately, is the percentage of human wee in the water supply, both before and after the wee was added to the reservoir?


PORTLAND, Ore. (AP) — …. Portland officials said Wednesday they are flushing away millions of gallons of treated water for the second time in less than three years because someone urinated into a city reservoir.

In June 2011, the city drained a 7.5 million-gallon reservoir at Mount Tabor in southeast Portland. This time, 38 million gallons from a different reservoir at the same location will be discarded after a 19-year-old was videotaped in the act. “The basic commandment of the Water Bureau is to provide clean, cold and constant water to its customers,” bureau administrator David Shaff said Wednesday….

The urine poses little risk — animals routinely deposit waste without creating a public health crisis — but Shaff said he doesn’t want to serve water that was deliberately tainted.

BONUS CALCULATION: Calculate the percentage of human wee in a standard (any standard) size swimming pool, both before and after one person’s wee was added to the pool.

BONUS CALCULATION: Calculate, approximately, the cost in dollars of administrator Shaff’s precautionary effort.


BONUS: Reports from Oregon Live, and from the Water Bureau.

BONUS: Wee mathematics in Texas (thanks to investigator Tom Gill for bringing this to our attention.)

UPDATE (April 17, 2014): Laura Helmuth wrote an essay, in Slate, about the mathematics of the Mount Tabor reservoir incident.

UPDATE (April 17, 2014): The AP presents video of the action.