In this experiment, determination of water hardness with EDTA. We test 2 samples from tap water. Sample 1 bring from tap water from house and simple 2 from tap water from MFU. When occurred there are different colour of tap water some clear water another be turbid. Therefore, water hardness due to Ca2+ and Mg2+ is titrated with standard EDTA using an Eriochrome Blak T indicator. Occurred changes colour form purple to dark-blue and record initial-final point find end point.