With increase in world population and subsequent increase in demand for food, the role of irrigation as a means of meeting this demand is bound to increase. Sources of irrigation water are surface and ground water, and reused wastewater. Irrigation though important in improving world food security can also have several adverse effects on the environment and on public health. These effects arise from the source and quality of irrigation water, the irrigation method and the run-off from the irrigated land. The main effects are transmission of water-borne disease, proliferation of disease vectors with subsequent increase in water-based diseases, toxic effects from chemicals in irrigation water, and pollution of water bodies by irrigation run-off. Measures to counter these adverse effects include management practices that promote health and fight disease, public education on the risks and protection measures, lowering the risk of human exposure to pathogens in irrigation water, lowering contamination of food crops through crop restriction thus reducing risk of infection to consumers, and setting guidelines and standards for reuse of wastewater. The Kenya Veterinarian Vol. 29 2005: pp. 130-134