Flush an average toilet, and you’ll hear a wet woosh, as if someone is dumping a pot of water on the ground. Flush one of three toilets in a science building at South Korea’s Ulsan National Institute of Science and Technology, and it will sound a lot different—just a tiny trickle of water, nearly drowned out by whirring. “We use a vacuum,” explained Jaeweon Cho, the mastermind of the toilets and an environmental engineer at the university, in a video describing his invention. Just before pressing the flush button, Cho…
