Assessment on physicochemical quality of tap and bottled water in Mekelle city, Ethiopia

Clean drinking water is a basic need for good health and an essential resource for communities around the world. In this study, the levels of six heavy metals, nine major ions and five physicochemical parameters in four different bottled water and two tap water samples from different sources that are consumed in Mekelle were investigated. Flame atomic absorption spectroscopy and UV – spectrophotometry were used for the determination of major anions and levels of major cations were determined. The mean concentration of Fe, Cu, Zn, Cd, Pb, Na+, K+, Ca2+, Mg2+, F−, Cl−, NO3−, SO42−, PO43−, EC and pH in water samples were found in the range [(0.82–0.9433), (0.39–0.6693), (0.055–0.2027), (0.0147–0.0213), (0.45–0.6567), (1.63–23.55), (0.01–2.75), (0.117–121.7), (0.073–15.33), (0.0019–0.153), (0.81–16.523), (0.15-6.1033), (0.2366–241.67), (0.0186–0.0286)] mg/L, EC (8.77–898.33 µs/cm) and pH (6.52–7.33), respectively. Not all the selected heavy metals (except Zn) were detected in all bottled water samples. All the heavy metals were detected in both tap water samples except Cr, which was not detected from Gerebsegen source (GS-1). All major anions (except F− and PO43−) and all major cations were detected in all water samples analyzed. PO43− was not detected in all bottled water samples and F− was not detected in BW1, BW3 and BW4. Major cations (Na+, Ca2+ and Mg2+) and major anions (Cl−, NO3− and SO42−) were found to be higher in BW4 than other bottled water sample. Concentration levels of all the heavy metals and major ions were found to be higher in the tap than bottled water samples. Concentration levels of all major cations (except K+), all major anions (except PO43−) and levels of all heavy metals (except Cu) were found to be higher in tap water sample from Aynalem source (AN-1) than from Gerebsegen source. Detected concentrations of Cu, Zn, Cr and all major ions in all water samples analyzed were below the maximum permissible level suggested by WHO and ESA. Concentrations of heavy metals: Fe, Cd and Pb in tap water samples from both sources exceeded the maximum permissible limit set by WHO and ESA. Therefore, all tested bottled water samples are safe for drinking. Relevant authorities in Mekelle Municipality should review water treatment processes or mechanisms and implement appropriate drinking water treatment (purification technology). This allows us to reduce the level of harmful substances to protect consumer health.