Water treatment plants In developing countries should use simplified technologies that require little automation or mechanization to lower capital costs significantly. Operations and maintenance should also be less costly and more suitable for local labor conditions. Use can be made of natural coagulants derived from plants and animals to reduce the cost of treatment.

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Dual distribution systems for nonpotable water reuse can help preserve high‐quality water supplies and reduce treatment costs. Growing urbanization has put a heavy demand on limited sources of water for public community water supply systems. A proven conservation measure to help meet increasing demand is the reclamation of wastewater for nonpotable purposes. Reclaimed water can be used for landscape and recreational grounds irrigation, industrial processes, cooling towers, air‐conditioning, stack gas scrubbing, toilet flushing, construction, firefighting, and environmental enhancement such as maintaining urban stream flows and wetlands. Urban reuse requires dual distribution systems that use one system for potable water and another for reclaimed water. Dual systems are particularly appropriate for urban developments now being planned, but they can prove cost‐effective even for systems that must be retrofitted. The economies arise from savings in the acquisition and development of new water sources and facilities and in wastewater treatment and disposal. Because the public health risk from nonpotable reuse is minimal, public acceptance is high and even enthusiastic. Nonpotable urban reuse is an option worth consideration by municipalities seeking additional water supply to meet future needs.

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