Water is one of the world’s most valuable resources, yet it is under constant threat due to climate change and resulting drought, explosive population growth, and waste. One of the most promising efforts to stem the global water crisis is industrial and municipal water reclamation and reuse. The Wate Reuse Association defines reused, recycled, or reclaimed water as “water that is used more than one time before it passes back into the natural water cycle.” Thus, water recycling is the reuse of treated waste water for beneficial purposes such as agricultural and landscape irrigation, industrial processes, toilet flushing, or replenishing a groundwater basin (referred to as groundwater recharge). Water reuse allows communities to become less dependent on groundwater and surface water sources and can decrease the diversion of water from sensitive ecosystems. Additionally, water reuse may reduce the nutrient loads from waste water discharges into waterways, thereby reducing and preventing pollution. This ‘new’ water source may also be used to replenish
overdrawn water sources and rejuvenate or reestablish those previously destroyed. The objective of the present paper is to give insight into the appropriate technology for treatment of waste water. The paper discusses sustainable waste water treatment systems in the context of urban areas of the developing world. The paper concludes that, “Since the urban areas of many developing countries are growing rapidly, ecological sanitation systems must be implemented that are sustainable and have the ability to adapt and grow with the community’s sanitation needs.” In order to determine the appropriate treatment system, the developer must consider the area’s climate, topography, and socioeconomic factors.