Sustainability of water supply is a key challenge, both in terms of water resources and sanitation scheme delivery. Access to safe drinking water and improved facilities are essential elements for human life. However, in most project areas, there is lack of sustainability of the water supply systems. The purpose of this study was to evaluate sustainability of rural water supply schemes in Kalu Woreda with identifying the reasons behind to low sustainability of rural water supply schemes and indicate the troubleshooting for non functionality per scheme system components at the stage of design, construction and service period. The study was carried out in six Kebeles of the woreda. The study employed descriptive survey design. The study was conducted by the source of primary data and secondary data collection methods and the study represented by simple random sampling methods both for population representation and water supply schemes select. Through random sampling, 200 households were selected for the study. The common rural water supply technologies include hand dug well, shallow well and spring development. All such by type have been studied and evaluated for their cause of non functionality. Statistical analysis using SPSS version 26 software was applied to analyze the data of water questionnaires and interviews. Quantitative and qualitative research techniques within a probability systematic and a non -probability purposive sampling methodology were used in this study. It was also found out that the sustainability of water supply scheme is assessed by using multi criteria analysis approach. Based on the general condition of the water supply scheme, technical, financial, social and institutional and there sub factor are weighted and evaluated by simple additive weighting method. Finally, the sustainability index value has been classified in three classes where, five water points belongs to poor sustainable class, nine has potentially sustainable and the remaining four has sustainable class. The results showed that average sustainability score across water supply schemes were 49.25%. This score indicated that the schemes were performing well on partial almost half of schemes. Laboratory analysis characterizing and evaluating its quality by comparing with WHO and Ethiopian Standards is used in this research for identifying water quality problems in the area. The water supply coverage was very low which covers only 54.56%. Besides this, a total of 38% schemes do not provide enough quantity of water to meet the 25 L/p/d national standards. Per capita water consumption in the Woreda is at only 13.375 liters. The research found that the most common non functionality causes are poor design, below the standard construction, poor institutional set ups of water supply infrastructures and poor quality of water. Therefore, proper construction, regular maintenance and control, working together with stockholders and creating awareness used as solution to mitigate the problem and sustainable use of water resources. Key words: Functionality, Multi criteria approach, Quality, Rural water supply, Scheme and Sustainable