Evaluating the impact of Nalla Lai contamination on drinking quality of groundwater in Rawalpindi city, Pakistan

The scientific report assessed the impact of Nalla Lai wastewater on the groundwater quality of Rawalpindi city, Pakistan. A total of 19 wastewater and 49 groundwater samples were collected during September and October 2016 and have been analyzed in the laboratory to detect different water quality parameters. The results revealed that BOD (biological oxygen demand), COD (chemical oxygen demand), iron, and cadmium values in many wastewater samples were beyond the recommended value of the National Environmental Quality Standards 1997 (NEQs, 1997). In groundwater samples, the results of iron, cadmium, manganese, zinc, TDS (total dissolved solids), pH, color, and hardness were found elevated from the standard values in one or more samples as compared with the National Standard for Drinking Water Quality, 2010 (NSDWQ, 2010). The decreasing metal concentration order in groundwater samples was iron > zinc > manganese > copper > cadmium. Very interestingly, hardness was found at elevated levels in 75% of investigated groundwater samples. Microbiological contamination was detected in 83% of the analyzed groundwater samples. The study revealed the percolation of heavy metals and microbial contamination in the bore water, tube wells, hand pumps, springs, and hand-dug wells located nearby the Nalla Lai wastewater stream.