There has been an urban legend for years that sewage systems in major cities have broken, due to so many people flushing their toilets at half-time of the Big Game. The facts are, there has never been a city’s sewage system overloaded during the game.
That doesn’t mean the systems don’t take a hit during halftime, in fact, 350 million gallons of water will flush through toilets from 90 million people using them. That’s the same amount of water that goes over Niagara Falls in seven minutes.
The urban legend probably started during Super Bowl 18 in 1984. During half-time the water main in Salt Lake City, Utah ruptured creating a mess in the capital city. Officials were quick to say the problem wasn’t caused by ‘half-time flushing’ but by the city’s old pipe system. The facts didn't seem to matter and ever since the urban legend has existed.
rotorooter.com