Development Of A Protocol For Evaluating Sand Dam Water Quality And Potability In Semi-Arid Areas: A Case Study Of Makueni County

Abstract

Sand dams have been recommended in many places as a feasible technology for the ASAL areas due to their ability to store water with minimal evaporation, recharge underground water and raise water table, among others. In Kenya, adoption of sand dam technology has been steadily increasing. Water from the sand dams is used for drinking, domestic uses, livestock watering, and for irrigation. Water quality is paramount for drinking water. However, much emphasis is being done on the sand dam technical aspects namely hydrologic measurement and analysis, and determination of the quantity of water that will be harvested with less or no concern on the water quality and how the water quality can be affected. There is no guideline on sand dam design parameters, location and method of abstraction for optimal water quality. There is need to investigate whether water from sand dams is suitable for drinking and develop a protocol to evaluate potable water quality from sand dams. The focus of this study was to determine water quality parameters for evaluating potability of water from sand dams, and development of a protocol for evaluating potability of water from sand dams in semi-arid areas. Water samples were collected from the sampled existing sand dams’ water abstraction points within Makueni County and analyzed for heavy metals, microbiological, physical and chemical quality. Laboratory test results showed that all tested sand dams within the study area have unsafe water for drinking in its raw form. A protocol for determining the potability of sand dams was developed. The protocol provides information on how to assess the quality of raw water from sand dams; to determine the need and extent of the water treatment to make it safe for drinking; and to examine the resultant to ascertain that it conforms to the recommended drinking water standards. The study recommends that the ‘Protocol for Evaluating Potability of Water from Sand Dams’ developed during this study be adopted before any sand dam is declared to provide safe water for drinking. It recommends that further studies on the effects of soil characteristics (within the dam site and upstream of the dam) on water quality be done.