An Investigation and Technical-Economic Comparison of Dual Water Distribution Network in the Old and New Textures of Yazd City

Given the reduction of quality and quantity of water sources in Yazd province, the consumption management approach should be considered. Separation of drinking water from sanitary water is one of the important components of quantitative and qualitative management of consumption. In the present study, scenario of dual water distribution network were evaluated in Gazorgah (old texture) and Safaieh (new texture) regions of Yazd province using EPAnet software in both technical and economic perspective. Investment costs of dual water distribution network in new and old texture are respectively 12595.1 and 20366.66 million rials. Current costs in new and old texture are respectively 736.80 (11.9% primary investment) and 1308.72 (6.4% primary investment) million rials. The cost of distributing each cubic meter of drinking water for dual water distribution network in old and new texture are respectively 113930 and 87630 rials. The results of economic analysis of the methods using Net Present Value (NPV) showed that both methods have positive NPV index, which shows the success of projects from an economic point of view. In relation to the comparison of the sales price of drinking water, the dual  water distribution network method in new texture with price of 46000 rials per cubic meter, relation to old texture with price of 60500  rials, has higher NPV and more economical. Estimated costs of dual water distribution network showed that in new texture was more costly than in old texture. The cause can be searched for in population density. As a result, dual water distribution network method is more economical in new texture. Because demand is higher in new texture. But since other parameters such as ease of access to drinking water distribution network, the age of the people, social acceptance is important, so in the old texture, dual water method is suggested. Therefore, by the implementation of this project, water conservation culture can be managed in a fair way through stable tariffs for drinking water and sanitary water rationing.