Investigation of Portable Water Quality and Provision in the City of Nairobi, Kenya

Abstract

Water quality is one of the indicators that can provide consumer confidence in drinking water distributed in the City of Nairobi. A safe water supply is crucial to public health hence the quality of portable water may have negative consequences on the general public health, the water’s taste and odour. Kenya’s capital city, Nairobi, faces several water challenges such as water shortages which could lead to the distribution of substandard water. The aim of this study was to investigate the portable water quality and provision specific to assessing point-of-use water treatment systems, determining selected quality parameters, evaluating the efficiency of water treatment techniques and assessing the portable water packaging for the various brands marketed in the City of Nairobi, Kenya. Water samples were randomly obtained from thirty two households, twenty eight shops and supermarkets and twenty eight water vending stations. The physical, bacteriological, and chemical properties of the water samples were analysed using spectrophotometry for the colour test, glass–electrode method for pH analysis, multiparameter-photometer for the Fluoride test, Microwave Plasma Atomic Emission Spectrometer for Iron (II), Manganese and Silicon ions, and Most Probable Number method for microbial tests. Analysis of residual Chlorine was done at the point of sampling as opposed to laboratory-based analysis of bacteria, pH, colour, conductivity and chemicals. The study indicated that 12.5 % of the household population living in Nairobi sterilized their water chemically or through boiling. Additionally, 87.5 % of the household population under study consumed untreated water. Water boiling was an effective method of water sterilization compared to the chemical method since it killed bacteria and viruses that are the major causes of waterborne diseases. The presence of Escherichia coli and faecal coliform contamination was detected in twenty of the sampled households. This represents 62.5 % of the household population consuming contaminated water. Bottled water from supermarkets and shops recorded nil of Escherichia coli and total coliforms. However, 50 % of water samples from vending stations recorded levels ranging from 1 to 35 MPN/ 100 ml of total coliforms while 18 % recorded 1 to 8 MPN/ 100 ml of Escherichia coli. Moreover, a total population of 6.82 % was found to be taking water with Fluoride above the recommended limits. The recommended Fluoride level in drinking water is 1.5 mg.L-1 according to KS EAS 153:2018 – standard on purified water and KS EAS 12:2018 – potable water specifications. The Point-of-Use treatment techniques found include boiling and use of Sodium Hypochlorite at 6.25 % in households, bottled water at 100 % in shops, kiosks and supermarkets, and reverse osmosis at 100 % in water vending stations. The quality of selected parameters was 13.6 % within the set specifications. This means, 86.4 % of the total population in the City of Nairobi is drinking unsafe water. The efficiency of the various water treatment techniques used for bottled water from supermarkets, shops and water vending stations was 80 %. Furthermore, portable water packaging compliance was 42.9 %. Households should consider boiling water as a means of treatment over the use of Sodium Hypochlorite. Additionally, Water quality should be monitored on a regular basis among vendors and bottling industries as Kenya Bureau of Standards strictly enforce compliance with portable water packaging. The findings of this study have revealed that the population of Nairobi is vulnerable to substandard water quality in terms of pH, colour, conductivity, residual Chlorine, Fluoride ions, Iron (II) ions, Silicon ions, Manganese ions, total coliform and Escherichia coli.