David Shaff, administrator of the bureau, said he decided to have the water drained after security cameras recorded a 21-year-old man, Joshua Seater of Molalla, urinating Wednesday into the Mount Tabor reservoir, which supplies drinking water to much of Portland, Portland cable news network NWCN reported Thursday.
"I had a pleasant buzz and I should have known better," NWCN quoted Seater as saying. "It was a split second thing and as soon as I was done I was like, 'Oh man' and I saw the police officer show up I knew exactly what they're here for."
Dave Stone, an assistant professor of toxicology at Oregon State University, said urine is generally sterile and would not pose any risks to those who drank the contaminated water, The Oregonian reported.
"It's inappropriate behavior. But how many animals are doing that or birds?" he said. "I don't want to second-guess the city, but I can't think of anything chemically that would have me be concerned."
However, officials said they are also concerned about unidentified objects Seater and four other people were taped dropping into the open reservoir.
Officials said the cleaning process is likely to take several days, but service to residents should not be affected.
NWCN reported the water is treated prior to entering the city's reservoirs.
"The water is chlorinated, but its chlorinated before the reservoirs so the water in the reservoirs is the water that you drink," city Commissioner Randy Leonard said.
Seater could face misdemeanor charges and fines, police said.
"I wouldn't mind paying for it, but I don't have a job right now," he told NWCN. "I'm willing to do community service to clean up the place because I feel bad and feel pretty stupid."