How Safe is the Water Consumed in Different Parts of Nairobi, Kenya?

Water is very important in human beings because it plays a greater role, in that it keeps the body properly hydrated for brain and body cells functioning among others. In the rural areas water may be supplied through pipes or directly taken from the sources such as Rivers, Oasis and Lakes, while in the urban areas water is mainly supplied in polyethylene terephthalate (PET) plastic made bottles. Heavy metals are among the major products that may lead to water contamination, which should be maintained below the permissible level by the health organizations. This project dealt with the analysis of contaminants in different types of water brands that are consumed in Nairobi County in Kenya. Seven trusted brands of bottled drinking water were obtained from some Supermarkets in Nairobi city and analyzed for heavy metals, which includes; Sb, Cr, Mn, Pb, Cd, Cu and Zn and the residue levels of physico-chemical parameters including pH, Electrical Conductivity (EC) and Total Dissolved Solids (TDS) were also determined. The heavy metals were analysed using Atomic Absorption Spectrometer (AAS) Spectra AA-10, while the physico-chemical parameters were analysed using the standard methods for the examination of bottled drinking water. The results reviewed that; antimony levels were Below Detectable Limit (DBL) in all the samples, while copper concentration ranged between BDL and 0.05 ±0.01 mg/g in all the samples, which was in the range stipulated by World Health Organization (WHO) and Kenya Bureau of Standards (KEBS) of 0.1 mg/g and 2.00 mg/g respectively. Lead concentration residue levels on the other hand ranged between BDL and 0.32±0.19 mg/g in the seven samples. Cadmium residue levels were Below Detection Limit (BDL) in all the samples analysed in the two projects, while chromium ranged between BDL and 0.66±0.03 mg/g. The concentration of manganese was in the range of BDL and 0.93±0.53 mg/g, Zinc was not detected in all the samples. Lead, Chromium and Manganese residue levels were all within the limit set by WHO and KEBS in most of the samples, but some of their levels were higher than those standards in only few water samples. The pH values ranged between 6.72 ± 0.15 and 7.32 ± 0.01 in all the samples. These values were all within the standard set levels by the health organizations, which are in the range of 6.0 and 9.4. These organizations include, National Environment Management Authority (NEMA), KEBS and WHO. The TDS levels were in the range of 26.80 ± 0.50 mg/l and 100.70 ± 0.08 mg/l, which were well below the set standards set by NEMA, KEBS and WHO of 1,500 mg/l each. On the other hand, the EC was in the range of 74.50 ± 0.05 µS/cm and 197.70 ± 0.02 µS/cm, which was within the range set by NEMA, KEBS and WHO of 25-2,500 µS/cm, 30-2,500 µS/cm and 26-2,500 µS/cm respectively. There is therefore, need for regular monitoring of pH values of bottled drinking water by the respective water bottlers.