Greywater, including water from washing machines, sinks, showers, and baths may be reused in landscape irrigation and toilets as a method of water conservation. Likewise, rainwater harvesting from storm-water runoff is also a sustainable method to conserve water use in a sustainable shelter.[35] Sustainable Urban Drainage Systems replicate the natural systems that clean water in wildlife and implement them in a city's drainage system so as to minimize contaminated water and unnatural rates of runoff into the environment.[36][37]