4.5.2  Water source contamination

Surface water can become contaminated in many ways. This may by direct discharge into the river from a sewer or pipe. Rivers and streams are considered to be convenient ways of disposing of wastewaters of all types, including domestic and industrial wastes. Industrial sources may discharge hazardous substances, as well as organic matter and suspended solids without adequate treatment. Surface water pollution can also come from stormwater run-off, which may carry contaminated materials into the water. Open defecation and the uncontrolled disposal of solid wastes are two likely sources of contamination by run-off.

Groundwater is generally cleaner than surface water for reasons explained earlier but pollution of groundwater resources has become a major problem in Ethiopia and around the world. Groundwater is polluted by the leaching of human and industrial waste, pesticides and fertilisers, which infiltrate into the aquifers from the surface and pollute groundwater supplies. Pit latrines that are located too close to a water source or are poorly constructed and maintained can also be sources of groundwater contamination. The polluted water reaches people and animals through contaminated spring and well water.