Assessment of the main causes of non-functionality of rural water supply schemes in LailayrnMaichew Woreda has been the main objective of this research. To assess the major causes ofrnnon-functionality primary and secondary data was collected from 407 rural water supplyrnschemes (RWSS) of the woreda. Secondary data was collected from respective governmental andrnnon-governmental organization at federal, state and woreda level. Primary data was collectedrnthrough questionnaire, key informant interview, focus group discussion and observation.rnThe secondary and primary data sources have been useful to assess all non-functional schemesrnin the woreda. All types of rural water supply schemes include hand dug well, shallow well,rnspring development at spot and deep well have been studied and analyzed for their main cause ofrnnon-functionality in the woreda.rnThe average non-functionality period of schemes in the study area is seven years. Most nonfunctionalityrnoccurs much lesser than expected design periods. Two third of water schemes failedrnlower than a minimum design period, which is 10 years. Compare to scheme type springrndevelopment at spot becomes the best scheme of the study area.rnThe main causes of non-functionality are technical problems including construction, yield,rnquality, site selection problems, management of operational and maintenance problemsrnincluding mechanical and management problems, financial problems, institutional problems andrnothers including social, cultural, gender, health and education problems. Among thosernindividual causes of non-functionality, financial problems score high (18.02%). Generally,rnmanagement of operational and maintenance problems score high (35.27%) and technicalrnproblems scores 33.02% which is the second main cause of non-functionality of RWSSs.rnThe researcher strongly recommended that community participation should be in all stage ofrnscheme development not only during construction, local well train construction and supervisionrnfirm should be available during scheme design and construction with standard design andrnconstruction manuals, technical training for community water committee and care takers shouldrnbe continuous throughout scheme design period and monitoring of schemes through therncoordination of different institutions should be develop for functional sustainability of RWSSs.