A third of the seven billion people on Earth are without sanitation, which puts their water supplies at risk. Sanitary sewer systems in the developed world are effective but not sustainable. To achieve a high level of efficiency, it is generally not advisable to mix or dilute different types of waste, and yet the current toilet and sewer systems mix and dilute urine and feces—with each other and with other liquids, including water. A solution to this problem could be “diversion.” Our body naturally separates urine (high in essential nutrients for plants) from feces (low in nutrients, but high in pathogens). Sewer systems which employ urine diversion have the benefit of producing waste which can be used as a fertilizer in developing countries, and in developed countries they reduce the load on nutrient removal processes. This technique is compatible with public sewer and centralized treatment systems in developed countries.