Why Do Some Toilets Have Two Flush Buttons?

As both evolution and classic literature have taught us, everyone poops. And yet not everything about that experience is universal: European bathroom stalls have doors that reach all the way across, for example (revolutionary, we know); in Japan, toilets come with their own soundtrack; in America, the water level comes almost up to your butt for some reason.

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There’s a lot of variation in how we all use the potty, is the point – and one minorly confusing thing you may have been faced with, particularly if you’ve traveled to Europe or Asia or just a slightly unusual home in the US, is a toilet with two flush buttons. Why? For what purpose? Wh… what does the other button flush??

Well, fear not. We’re here to solve all your toilet-related woes. The reason for the two-flusher system is both simple and sensible: it’s to save water by allowing the user to decide how much of a flush they need.

“The primary reason European toilets have two buttons is to save water,” explains Chinese toilet manufacturer Danube Toilet. “Water conservation has been a central concern in Europe for decades, and the dual-flush system was developed to address this issue.”

Usually, the two buttons will be different sizes – pressing the larger one (or, if they're the same size, both together) will trigger a “full flush”, and the smaller one a “half flush”. The reason is obvious to anybody familiar with the old aphorism of “if it’s brown, flush it down; if it’s yellow, let it mellow” – put bluntly, pee needs less water than poop to get properly washed away.

The result is that dual-flush toilets typically use much less water than single-flush models. In places like Australia, where water conservation is a top priority, it makes them such hot commodities that the government has actually paid people in the past to change their house’s plumbing. 

“Single flush toilets are one of the biggest users of water in [New South Wales] homes, using 12 liters of drinking water with every flush,” pointed out the state’s Toilet Rebate site in 2010. “A dual flush toilet can reduce this to 4.5 liter & 3 liter flushes, and save households around 25,000 liters of water a year.”

So, if you’re ever faced with one of these dual-flush toilets, don’t panic. Just remember: if you’ve laid a log, go whole hog; if you’ve just been piddlin’, press the littlun.