We recycle newspaper, bottles and cans. So why aren’t we recycling our own water? Instead, the water we use goes down the drain. But sewer systems are big, centralized systems that are expensive to maintain. So German wastewater engineer Erwin Nolde has come up with an alternative, which he’s now testing in a Berlin neighborhood. Here, 250 people are reusing kitchen and laundry water through an on-site treatment plant at their apartment block. His bigger vision to go off the water grid entirely. And so a Berlin seven-story public housing complex features a courtyard which has been converted into an “urban garden” with two functions: recycling rainwater from roofs into a greenhouse, and treating non-toxic greywater from apartments. “We can make high-quality drinking water from rainwater,” he says, “the rest of the water we can recycle several times.” While household greywater treatment systems aren’t new, apartment-sized ones are rare.