The United States uses more water per person than any other country . The average person in the United States uses about 70 gallons per day indoors (265 L/day) , and, with 30 percent of residential demand for outdoor use, the average US resident also uses around 30 gallons per day outside (114 L/day).
Through the implementation of low-flow devices and a composting toilet, we plan to reduce this number to less than 20 gallons per capita per day for indoor use (<76 L/day). We estimate our total plant irrigation water demand at ~26 gallons per day (99 L/day). Non-potable water can satisfy over three-quarters of daily water demand in the United States, potentially being used for clothes washers, toilets, and outdoor activities, such as irrigation . To further reduce water consumption within reACT, we plan to both harvest rainwater and recycle greywater. Greywater is domestic wastewater that has not been contaminated with sewage or food waste. This consists of effluent streams from bathtubs, showers, bathroom lavatories, and clothes washing machines.
Rainwater will be the cleanest source of water aside from a municipal connection. This means that rainwater will be the easiest to treat for both potable and non-potable use. The dirtiest form of water, black water, is absent from reACT because there is no water-based toilet in the house. The remaining water, which is captured from various household appliances, is greywater. We classify greywater into two distinct categories, dark and light greywater. Dark greywater contains food-based contaminants such as oils, greases, and large solids, and is sourced from the kitchen sink and the dishwasher. Because of its contaminant composition, dark greywater is significantly more difficult to treat than light greywater, especially on a residential scale. Light greywater in reACT comes from the washing machine, shower, and bathroom sink. For the purposes of water recycling, we will only pull from the light greywater, dumping the dark greywater into our equivalent of a septic tank. In our quest to become net-zero in water usage, we will rely on rainwater to replenish consumed water and dark greywater.
Potable water is water treated to drinking standards. In reACT, Non-potable water will be considered water that has been treated to allow longer term storage, but not purified to drinking standards. Non-potable water can satisfy over three-quarters of daily water demand in the United