Buzz
Erin from Baltimore reached out with a curious question: why does the water in her toilet bowl ripple when it's windy outside? It’s one of those odd queries – akin to Jason’s question about his dog’s popcorn-scented paws – that makes you pause and wonder if it’s a joke or a peculiar phenomenon everyone else knows about.
After some research and a rather unusual morning spent observing my toilet (yes, this is the glamorous life of a science writer), I discovered Erin wasn’t pulling my leg. Maybe I’m among the few who never noticed toilet water reacts to wind. Well done, Soniak.
But what exactly triggers this bathroom phenomenon?
In numerous households across the U.S., a key component of the plumbing system is a pipe that extends upward and exits through the roof. Known as a 'vent stack,' this outlet ensures sewage gases are expelled outside rather than through fixtures like toilets, sinks, or tubs, which would otherwise fill the home with unpleasant odors. Additionally, the vent stack facilitates airflow within the pipes, ensuring wastewater drains efficiently and minimizing disruptive gurgling sounds.
When wind passes over the vent stack’s opening on the roof, it reduces the air pressure inside the pipe. This phenomenon is explained by Bernoulli’s principle ('as the velocity of a fluid increases, its internal pressure decreases'), the same principle that enables airplanes to achieve lift. The drop in pressure within the pipes generates a mild suction effect across the plumbing system, tugging at the water in the toilet below. As wind intensity fluctuates, the suction varies, causing the toilet water to move in response.
