Water scarcity is seasonal in many regions, and harvesting and storing rainwater is an effective way to prepare. Another approach is to reuse domestic graywater. Gardens and green roofs can be used as cisterns for this purpose.
João Manuel Feijó, an agronomist and specialist in biophilic design, explains that graywater is wastewater from showers, sinks, bathtubs, washing machines, and dishwashers. It accounts for a large percentage of residential wastewater: between 50% and 80%.
