Being water is highly consumed by human being; it becomes a media for the intake of unwanted elements, compounds, substances and micro organisms into the body. Which may lead to very dangerous diseases and fatel accidents. Even from 2000 BC this awareness was there. There was lot of description about the method of purifying water in the Sanskrit Book “Sushurt Samhitha”. In 1880 a Chemical section of the American Association appointed a special committee to study out this matter in detail. In 1889 and 1895 this committee were submitted their findings and suggested some standard method for the analysis of water chemically and micro biologically. In 1895 American Public Health Association (APHA) Committee has appointed, to draw up procedure for the study of Bacteria in a uniform manner and with special references to the differentiation of species. In 1895 the report has submitted and find out with wide acceptance. In 1899 APHA appointed a committee to constitute a standard for the limits of elements, compounds, substance all micro organisms count etc. in consumable and harmless water for human being which we called as an APHA standard.  APHA along with Pollution Control Federation has revised this standard many times. According to it the possible impurities and its limits in portable water is as below.