One of the big stories that goes around in tornado country is that tornadoes can suck the water right out of your toilet. It's true. A storm chaser riding out the hurricane in Bermuda noticed that the storm sucked the water out of his toilet, too. Here's how that works.
Mark Sudduth, whose handle is @hurricanetrack on Twitter, posted a video of the gurgly toilet in his hotel room to Instagram on Friday night during some of the worst winds in Hurricane Gonzalo as it passed over the island.
Even though our toilets flush into pipes that lead underground, they're still affected by weather conditions outside. All buildings with indoor plumbing are required to have a vent in the roof of the building. These vents are there for two reasons: 1) it allows gasses to vent outside as opposed to into the building, and 2) the open vent helps water and sewage flow through the pipes.
Just like a chimney or a leaky window, these vents are susceptible to windy days.
When a strong gust of wind blows over the top of these vents, the fast-moving air creates an area of low pressure at the top of the pipe. This low pressure causes the air within the pipe to rush up to fill the void (nature abhors a vacuum), creating suction within the building's pipes. If the sucking is strong enough, it can briefly tug on the water in the toilet. The water sloshes back up once the wind gust resides. Exceptionally strong gusts of wind, such as those seen in hurricanes or tornadoes, make this effect especially pronounced.
You can even see water subtly sloshing around on a regular ol' blustery day. It's a pretty cool effect, for as much as what goes on in a toilet can be considered "cool," anyway.