According to Popular Science –
Unfortunately, installing a new toilet is space is as messy as it is here on Earth. According to NASA, the leak sprung while astronauts on the American side of the station were unhooking a connection point from the potable water system. About 2.5 gallons of water spilled out, and the astronauts had to soak it all up using—what else—towels!
DUMMR.com 