This study focuses on the investigation of the drinking water quality problems of Sherkol Town from the source to points of distribution in relation to safety and acceptability for users concerning water quality parameters and also identifying the relationship between the residual chlorine and pressure in the gravity distribution of the water supply systems. The town gets water supply from a Sand dam of Sherkol river treatment plant. To achieve the objectives, the researcher was collecting samples from diff erent locations of the study area and conducting laboratory analysis with field measurement data and applying WaterCad simulation model to identify the pressure effect on residual chlorine in water distribution net work system. Physico-chemical and bacteriological parameters conducted in the whole 12 representative samples of randomly selected from sensitive areas for expected pollution such as raw water, treatment plant, service reservoir and also nine water points including house hold connection were slelected from service reserviour to end coustemer users in distribution net work system, for physico-chemical and biological analyses to investigate the drinking water quality problem. TheresultswereanalysedandinterpretedbyusingMicrosoftexcel,GlobalmapperandWaterCade softwares.Theresultsobtained before chlorination in the reserviour showthatiron was found between 0.48-0.57 mg/l, Turbdity 47-161UTN and many bacteria which were above WorldHealthOrganization(WHO)permissiblelimit but the remaing parameters were in the WHO & Ethiopiarecommendedvaluespermissiblelimitfordrinkingwaterquality. In the distribution net work alloftestedsampleshaveresidualchlorinebelowtheWHOminimumpermissiblelimit(0.2mg/L), the turbdity was found in the range of 37 and 65 UTN, bactrologically only 33.3% of the samples tested were free from phatagonic Micro Organisms (E-coli & Total coliform) and removal efficiency of the WTP revealed 70.81% and 77.64% before and after chlorination respectively in terms of Turbdity removal. However,theaestheticandacceptabilityofphysicalparameterslikecolourandturbiditywereabovethemaximumpermi ssiblelimitofbothWHOandEthiopianrecommendedguidelineforpermissiblelimit.Althoughfurtherresearchisrequir edtodrawultimateconclusions,atthispointitcanbeconsideredthatthereisnohealthsignificanceontheusersconcerningt hephysico-chemicalparameters.Similarly,theresult of bacteriological analyses indicated 33.3% of samples showed low risk and 33.3% samples were obserbed intermediate risk at furthest water points. Modeling results showed that the residual chlorine concentration in distribution system is relatively less at maximum presure than pressure but both shows less than 0.2mg/. and along with these water quality simulation results illustrated water quality deterioration due to availability of minimum residual chlorine which is below WHO guideline. To overcome these problems improving the removal efficiency of treatment plant by up grading treatment plant with simple aeration system followed by slow sand filtration will reduce the concertation of iron and turbdity of the water source as well and installing suitable semi authomation chlorine dosing system is recommended to obtain optimum residual chlorine dose in the system. KEYWORDS:Waterqualityparameters,WHOstandards, Ethiopian recommended limited value,Pressure, residual chlorine.