This　paper　proposes　a　new　method　to　evaluate　junctions＇　water　demands　in　pipelines　system　by　classifying　users＇　demands　patterns.　Further　more,　GIS　(geographic　information　systems)　spatial　analysis　technique　is　applied　in　accessing　customers＇　water　payment　data　from　utility＇s　billing　database　so　that　customers＇　base　demand　and　junction　water　demand　can　be　calculated.　A　solution　is　given　for　computing　unaccounted　for　water　including　leakage　losses,　water　supplying　and　water　demand＇s　computational　value　are　adjusted　to　balance.　Finally　a　real　engineering　demo　is　presented.