Investigation of the Drinking Water Quality of Kithimani Area in Yatta District





Although the world is blessed with enormous water resources, <2% is available for use in irrigation, industry and domestic purposes, since more than 98% is saline. In addition, most of the water sources of the <2% deemed available are heavily contaminated and cannot be used directly without treatment. The situation is worse in Kenya, and the country is already classified as a water scarce country.


The main objective of the study was to assess the quality of drinking water in Kithimani area. Kithimani is the headquarters of Yatta district and is located approximately 150 km from Nairobi. The main sources of water are: Shallow wells, a government dug borehole ( Utumuoni) and the Athi River. Specifically the project investigated the physio-chemical parameters (pH, conductivity, salinity, TDS, DO, Chlorine, turbidity, Color, hardness, phosphates and nitrates); the heavy metals (lead, chromium, cadmium) and 17 organochlorine pesticides (Methoxychlor, DDT, Endrin aldehyde, DDD, Endosulfan, Endrin, Dieldrin, DDE, α-HCH, β-HCH, γ-HCH and δ-HCH). Water was collected from the three sources and characterized following different standard methods.


The results revealed variations in the concentrations across different parameters and different sources. The mean pH varied between 8.02-6.24, conductivity (295-737 µs/cm), TDS (3.11-4.01 mg/l), Dissolved oxygen (4.76-4.93 mg/l), salinity (3.11-4.01 mg/l), colour (130-184 CU) turbidity (0.70-98), Total chlorine (0-68 ppm), phosphates (0.37-1.72 ppm), lead (<0.02-0.075 ppm), cadmium (<0.001 ppm), chromium (< 0.005 ppm). For the organochlorine pesticides methoxychlor (5.12-5.97 ng/l), p,p’-DDT (7.01-7.37 ng/l), Endrin aldehyde (3.97-4.58 ng/l), p,p’-DDD (4.13-6.96), Endosulfan II (5.00-7.57 ng/l), Endrin (4.01-5.66 ng/l), Dieldrin (23.06-24.11 ng/l), p,p’-DDE (1.01-2.93 ng/l), Endosulfan I (5.93-9.83 ng/l) Heptachlor epoxide (3.43-3.88 ng/l), Aldrin (3.02-3.61 ng/l),  δ-HCH (2.37-9.88 ng/l), γ-HCH (3.95-9.43 ng/l), β-HCH (0.74-1.01 ng/l), α-HCH (7.13-8.46 ng/l)


Most parameters investigated were below the drinking water guidelines set by the World Health Organisation and the National Environment Management Authority of Kenya (NEMA), except for pH of the shallow water well (<6.5 limit), conductivity for all sites (>5.8 µS/cm), turbidity for Athi River and shallow water well (>1.0 NTU), color for Athi River and the Shallow well water (>15 CU) and lead in the Athi river water which was quite high ( > 0.01 ppm). This shows that despite the efforts by NEMA’s to clean the upstream of the Nairobi River, heavy metals still find their way into the river at levels that could cause toxicity effects to aquatic organisms and human population who use the water in the downstream. 

Key words: Kithimani, water quality, heavy metals, pesticides pollution

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