Comparison of the water quality between depurative water and tap water

Objective:To investigate if depurative water was better than tap water in sensory properties,general chemical characters,toxicology and microorganism index.Methods: Five pairs of tap water and purified water were sampled from five residential areas in Taiyuan.Turbidity degree,pH,total hardness,dissolved oxygen,levels of aluminum,iron,manganese,zinc,selenium,mercury,arsenic,lead,cadmium and total chromium,total coliform group were detected by corresponding methods.Results: The levels of cadmium and iron in all tap water samples exceeded the limit in sanitary standard for drinking water,however,the exceeding proportions of cadmium and iron in depurative water were 40% and 80%.Other three kinds of index in these two water samples were conformed to meet the standard.Conclusion: The concentrations of cadmium and iron in tap water exceed the standard in some areas of Taiyuan.Total hardness of depurative water is lower than tap water,toxic heavy metals in depurative water are much safer compared with tap water.