Monitoring and assessment of water quality in Tehran city using physicochemical and microbial indexes

Drinking water is one of the main factors for health maintenance and sustainable development of communities and its quantity and quality are so important. The aim of present study is random sampling of drinking water in 30 regions of Tehran city during 2 months in summer of 2020 to determine physicochemical attributes, microbial quantity and heavy metal levels according to national standard guidelines. Tests such as pH, alkalinity, turbidity, electrical conductivity, chloride, nitrite level, total and thermotolerant coliforms, and also heavy metals (arsenic, copper, zinc and lead), were performed in three replications. The pH (6.50 to 7.81), turbidity (0.011 to 2.983 NUT), chloride level (240.42 to 321.34 mg/L) and nitrate value (7.21 to 20.04 mg/L) were in allowable ranges. The phenolphthalein alkalinity was not found and methyl orange alkalinity was detected in the range of 31.54 to 147.22 (mg/L) in samples. The electrical conductivity (1401.7 to 1972.1 μs/cm) and thermotolerant coliforms were found higher than allowable range in some samples. The range of heavy metals was represented by following trend in Tehran: arsenic (0.85 to 15.90 μg/L), cooper (0.04 to 3.38 mg/L), zinc (0.16 to 3.80 mg/L), lead (0.001 to 0.031 mg/L) and some ranges were not within the national standard guidelines. The present study illustrated that quality of drinking water was in line with World Health Organization, while microbial quantity, electrical conductivity and some impurities (Cu and Pb) were higher than standard in some regions, so more arrangements should consider for increasing of drinking water quality in Tehran.