This sort of thing is not supposed to happen in a marquee city, but 1.3 million people in Montreal have been ordered to boil their water before drinking it, reports the Montreal Gazette. The 24-hour advisory covers most of the 1.8 million residents of Canada's second largest city, notes the BBC. Something went wrong during maintenance at a water-filtration plant, causing the water level in a main basin to dip lower than expected. The mishap stirred up sediment that is now turning up as brown tap water, and authorities are testing to make sure no bacteria snuck in, too. (More Montreal stories.)