Investigation of Corrosion Potential and Precipitation Tendency of Drinking Water in the Qorveh Distribution System By using Langlier and Rizner Indexes

Established standards show that water should not be corrosive. Corrosive waters dissolve materials of which pipes, junctions, valves of municipal water delivery systems are made from and cause different hygiene, aesthetic, and economical problems in such water delivery systems. In addition, carbonates precipitation tendency of water due to creation of different layers in the pipes reduces pipe diameter and consequently reduces discharge of water in the pipes. Main of this study is investigating Langelier Saturation and Ryznar Indices. For determining the aims of the research 120 samples were obtained monthly in different days. Duration of sampling was about 9 month. By considering standard methods, obtaining of samples was conducted coincidentally at different parts of reservoirs, and distribution network. Analysis of TDS, calcium hardness, alkalinity, temperature, and pH were done for each sample. Calculation of Langelier Saturation and Ryznar Indices were done by determining the mentioned parameters. Results show that mean and standard deviation of Langelier Saturation Index are 0.32 and 0.31, also mean and standard deviation of Ryznar index are 6.75 and 0.35, respectively. Results of this study indicates that municipal water of Qorveh city is corrosive and have tendency to precipitation. In order to solve this problem, a complete network of analysis for determining the reasons of this phenomena is suggested.