Ensuring functional sustainability of water and sanitation developments throughout the design period isrnvitally necessary. It helps to identify the main causes of non functionality and indicate the troubleshootingrnfor non functionality per scheme system components at the stage of design, construction and servicernperiod.rnTo identify the major causes of non functionality the research has employed both primary and secondaryrndata sources. Secondary data was collected from respective governmental and non-governmentalrnorganization at federal, state and woreda level. Primary data, on the other hand, was obtained usingrnquestionnaire, Focus group Discussion (FGD) and observation.rnData from the secondary and primary sources enabled the researcher to scan and investigate more than 95rn% of water and sanitation schemes in Chencha woreda rural areas. The common rural water and sanitationrntechnologies include hand dug well, shallow well, spring with gravity distribution, spring at spot andrnsimple pit latrine. All have been studied and evaluated for their cause of non functionality.rnThe research found that 87 % of non functionality occurred before its estimated design period, which isrnwithin ten years. But the average non functionality occurrence of the schemes is between six years up tornseven years. The most common non functionality causes are poor design, below the standard constructionrnand poor institutional set ups of water and sanitation infrastructures. It includes: spring capping failure,rnmanagement and financial problems, construction materials problems, source yield decreasing, poorrnquality of water, pumping system failure, poor quantity of water and pipe line failures.rnWater and sanitary schemes are functionally sustainable, only when social, financial, technical,rninstitutional and environmental factors are integrated with every project life stages. The stages are needsrnassessment, conceptual design, design and action planning, implementation, and operation andrnmaintenance. To get rid of non functionality every system component design and construction activityrnshould be in accordance with the applicable design and construction methods.rnAll respective governmental, nongovernmental and community stakeholders should carry outrnresponsibility for functionality and sustainability of water and sanitation schemes. It is impossible to meetrnthe functionality of water and sanitation schemes developments, without the integration of all respectivernbodies in all project life stages through feasibility study, designing, construction and service periods