When it comes to wasting water, bathrooms are America’s top culprit. According to the U.S. Environmental Protection Agency, toilets can guzzle 27 percent of a home’s daily flow – or about 75 gallons a day for a family of four. Showers consume another 17 percent.

That’s a lot more than people use in Europe or Asia. It’s also squandering a vital resource. Just 3 percent of Earth’s water is fresh, and much of it lies trapped in glaciers, which helps explain why 750 million people around the world lack access to safe drinking water.

A team of engineering students from New York’s Cooper Union has designed a clever way to slow the flow.

Their dual-flush toilet converter consists of a container that fits into the toilet tank. Inside is a valve that lets through smaller or greater amounts of water as required. And, unlike similar devices, it can be installed in seconds, without tools.

“The rest of the world is already using dual-flush toilets,”Eric Nguyen, an electrical engineering student at Cooper Union who developed the device along with fellow student Abiyaz Chowdhury, told Live Science. “America seems to be one of last developed countries to step up to the plate and save water.”

Their device, which the pair invented during Cooper Union’s six-week Invention Factory summer program, was selected by start-up incubator Quirky to be developed into a product.