There are 3 types of water that can be referenced here. There is your black water, your gray water, and your white water. The reason for the colors is these are the pipe colors that would be used to carry the water source.
Black Water
Black water is dirty water and must go to the septic tank, or the sewage system. Once the water goes to the sewage system, it will go to a treatment center owned by KPW. The sewage treatment will be used to create ethanol fuels, and fertilizer. Black Water can not be reused.
Gray Water
Gray water is water that goes down the drains from bathing, washing dishes, and so on. Exceptions will be laundry, and toilet usage which will always be considered as black water. Gray water can only be used if there is a gray water holding tank. If not, gray water will have to go to the sewage system. Gray water can be used for toilet water, and watering outdoor space such as plants, and yards.
White Water
White water is clean water either from a well, or from KPW. White water can be used for everything that water will be needed to be used for. This includes drinking, cooking, and washing. When coming from KPW, it would have been chemically treated to kill any bad bacteria, and try to make the water as safe and as clean as possible.