Water quality assessment (WQI) of distribution network in selected elementary schoolsin the district 4 of Tehran metropolis in 2019

Optimal utilization of water resources such as lake and dam water reservoir requires proper monitoring methods and maintaining their quality to improve health. With reducing the quantity and quality of water, assessment of drinking water quality has recently found great importance.Water quality assessments have a very useful role in the conservation of water resources. Increasing water demand has resulted in increasing the importance of assessing the water resources quality. Therefore, the water quality assessment index of the distribution network of the schools seems to be necessary due to the exposure of children, as a sensitive and vulnerable group, with water pollutants. The purpose of this descriptive cross-sectional study was to investigate the water quality index of the water distribution network of elementary schools in district 4 of Tehran metropolis. This research was carried out by descriptive-analytical random cluster sampling in 10 drinking water distribution networks of primary schools in the metropolis of Tehran. The study was conducted in selected elementary schools in district 4 of Tehran city, from April 21 to May 22, 2019. The water samples were taken from 10 taps of 10 selected elementary schools to assess physicochemical variables of drinking water such as nitrate, nitrite, dissolved oxygen, electrical conductivity, hardness, and pH of water at standard conditions. All results were compared with the standards and water quality index of each elementary school was determined. Mean values of residual chlorine, temperature, turbidity, pH, total hardness, total organic carbon, total dissolved solids and electrical conductivity are 0.4±0.18(0.0-1.6) mg/l, 16.4±2.67(12-21)°C, 1.19±2.07(0.7-2.0)Nephlometry, 7.4±0.20 (2.6-7.7), 212.11±5.83(200-230)mg as CaCO3/l, 0.022±0.004(0.015-0.029)mg/l, 262±119.05(100-400)mg/l and 363.5±180.66(153-593)μmoh/cm. Based on the results, the water quality of the distribution network of the schools was rated as very good (0-49). This study showed that maintaining the water quality of the distribution network requires thecomprehensive water quality managementplanning