Human Health Risk Assessment and Water Quality Index of piped water supply system in Gulshan-e-Iqbal Town, Karachi (A Preliminary Town level study)

Abstract

In the present study, piped water samples from Gulshan-e-Iqbal Town, Karachi, were evaluated for their Health Risk Assessment (HRA) and Water Quality Index (WQI). For this, different physicochemical and microbiological parameters were analyzed, and the results were evaluated according to the guidelines established by the WHO (2011) and the National Standards for Drinking Water Quality (NSDWQ) (2008). With the exception of sulphate, all physicochemical parameters were well within the guideline values. The mean concentrations of the metals in the samples were in the following order: Ca²⁺  > Mg²⁺  > Zn > Fe > Pb > Ni > Cr > As. More than 70% of the samples tested for Total Coliform Count (TCC), Total Faecal Coliform Count (TFC), Total Feacal Streptococci (TFS), and Total Aerobic Count (TAC) were feacal contaminated. E. coli was also isolated in almost 84.61% of the tested piped water samples. Results from the WQI revealed that 95.6% of samples had good physico-chemical characteristics, and 26% of the piped water samples had good microbiological quality. The WQI readings of all the samples for metals showed that they were unfit for human consumption. The mean Chronic Daily Intake (CDI) and Hazard Quotient (HQ) values, respectively, were in the following order: Zn > Fe > Pb > Ni > Cr > As, and Pb > As > Ni > Cr > Zn > Fe. All HQ values for As and Pb were greater than 1, and 50% of piped water samples had an HQ value for Ni that was greater than 1, indicating that people may suffer serious health issues as a result. All of the piped water samples except the area of block 13 D (S-5), had HQ values of less than 1 in relation to iron, but Zn HQ values of less than 1 indicated only mild health problems. Discharge of untreated sewage and cross-contamination are all potential sources of contamination that could result in diseases that are harmful to the public’s health. Water monitoring and management projects should be implemented in order to improve pipeline infrastructure and reduce sewage leakages.