Abstract:
Water samples for physico-chemical, heavy metals and bacteriological analyses were collected from 4
selected points along Mitheu Stream flowing through Machakos Municipality once every month from
June 2019 to September 2019. The samples were analyzed in Kenya Plant and Health Inspectorate
Service and Water Resources Authority laboratories then data subjected to one-way analysis of
variance to test significant differences (P≤0.05). The results were compared with World Health
Organization guidelines to assess the suitability of the water for irrigation use. Results showed that the
levels of the Biological Oxygen Demand and the Chemical Oxygen Demand in Mitheu Stream were
higher than critical values permitted by the World Health Organization for irrigation water. Nitrates and
Sulphates were within critical limits; however, Phosphates were higher than permissible limits at all the
sampling points. Heavy metals concentrations for Cu, Pb, Zn and Cr were within allowable limits for
irrigation water, but Cd was above the limit. Both total coliforms and Escherichia coli counts exceeded
allowable limits for irrigation water. As such, Mitheu Stream can be considered polluted and the water
unfit for irrigation farming. The Municipal authorities, working with other relevant stakeholders should
take appropriate measures to mitigate stream pollution from untreated effluent discharged into the
stream.
