Assessment of Physico-Chemical and Microbiological Properties of Shallow Well Water in Kawangware Location, Nairobi City County, Kenya
Njiraini, Beth Waithera
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Lack of access to clean drinking water adversely the public health. Kawangware location is undergoing rapid expansion in population, economic growth and urbanization. One of the challenges of this growth is pressure on public water supply. The inconsistent and inadequate water supply for the inhabitants has led to majority of the population relying on ground water for domestic and commercial uses more so, on shallow wells which seem to be relatively cheaper to construct. This has increased the vulnerability of underground water sources to sewage and waste water contamination and therefore exposing the population to infections by various water borne pathogens such as bacteria, viruses and protozoa. The aim of this study was to determine the quality of shallow well water used by households in Kawangware Location and compare it with the Kenya Bureau of Standards for drinking water. Water samples were from the three sub-location that is Kabiro, Gatina and Kawangware. Cross-sectional Survey research design was used and was accompanied by laboratory tests to analyze the level of each parameter from twenty eight shallow wells. A total of 112 samples were collected. Water samples were collected in the morning and evening in the month July and August 2017.The collected samples were analyzed for temperature using a mercury thermometer; pH, electrical conductivity, turbidity and Total dissolved solids was determined using portable meters. Zinc, iron, cadmium and lead were analyzed using Atomic Absorption Spectrophotometer, potassium and sodium using a flame photometer, total hardness was analyzed using titration, nitrates, phosphate, and bacteriological analysis were tested in accordance with the Standard methods for the Examination of water and waste waters. Derived values of tables and graphs were adopted for data presentation. The measurements physico-chemical parameters were as follows: in Gatina all parameters were within KEBs drinking water standards except for turbidity value which ranged from 0.6-78 μS/cm, NO3- value ranged from 17- 19.5 mg/L,PO32- ranged from 0.02-15.8mg/L, Cd ranged from 0.03-0.06 mg/L and Pb ranged from 0.01-1 mg/L. In Kawangware site all the parameters were within KEBs drinking water standards except for turbidity value which ranged from 0.0-50.1 μS/cm, NO3- value ranged from 17.5-19.7mg/L,PO32- ranged from 0.02-42.8 mg/L, Cd ranged from 0.03-0.05 mg/L and Pb ranged from 0.06-0.09 mg/L. In Kabiro site all the parameters were within KEBs drinking water standards except for turbidity value which ranged from 0.0-100.9 μS/cm ,NO3- value ranged from 14.3-20.1 mg/L,PO32- ranged from 0.04-14.0 mg/L and Cd ranged from 0.03-0.06 mg/L.The result obtained for the microbial analysis indicated that all the water samples analysed from the shallow wells in Kawangware location were contaminated with both total coliform and faecal coliforms. The highest counts of total coliform was 1637 MPN/100 ml and was recorded at Kabiro whilst the lowest counts of 1013 MPN/100 ml was recorded at Kawangware. At the same time, the water from all the sub-location had faecal coliforms with Gatina sub-location recording higher numbers (434 MPN/100 ml) followed by Kawangware (298 MPN/100) and finally Kabiro (271 MPN/100 ml). The results of the study also revealed that the physico-chemical parameters of ground water were significantly different (P≤0.05) from the recommended levels by the KEBS (2010).Parameters like Nitrates, phosphates, turbidity, lead, cadmium, coliforms levels and feacal coliforms exceeded the KEBS standards with the rest being within the acceptable levels. The difference was not significant (p≤ 0.05) between the levels of turbidity, Iron and phosphates and that of KEBS. The ground water in the area is not safe for drinking due to elevated levels of Nitrates, phosphates, turbidity, lead, cadmium, total coliforms levels and feacal coliforms which poses a great health risk to the public therefore there is need to supply safe water for domestic purposes.