It is very crucial for man to use clean water for drinking, domestic use, agriculture, food production or other purposes, since it has a great impact on health. The concentration levels of Cu, Cd, Mn, Fe, Ni, Pb and Zn in borehole and surface water of Kilimambogo region were measured using the atomic absorption spectrometer (AAS). pH of the water samples was also measured on site using a digital pH standard meter. The study area surrounds the Kilimambogo Mountain and has many pineapple plantations from Delmonte Kenya. Fertilizers and chemicals from the farms spill over to the neighbouring farms and contaminate the water table. Samples were analyzed from boreholes and surface water in the wet and dry seasons. The mean measured metal pollution indices (MPI) for surface water samples were 8.93 and 4.92 with a range of 6.92-13.23 and 0.97-10.45 in the wet and dry seasons, respectively. That of borehole water samples was 7.60 and 6.94 with a range of 3.96-9.95 and 2.67-11.19 in the wet and dry seasons, respectively. The pH levels ranged between 6.32-7.32 and 6.93-7.64 in the borehole and surface samples, respectively. The mean heavy metal pollution indices in borehole samples were 4369.52 and 4784.20, while that of surface samples were 4890.19 and 5222.81 in wet and dry seasons, respectively. These values exceeded 100, the set critical threshold value, hence the water sources in the region are highly enriched with heavy metals. These sources should be periodically monitored so that the cause and solution is established.
Keywords: Heavy metal, drinking water, health risks, Kilimambogo region.