The Jal Jeevan Mission of the Govt. of India promises clean and safe piped drinking water to all households by 2024. With a view to monitor the quality of the water being supplied at present, the Ministry of Consumer Affairs and Public Distribution commissioned the Bureau of Indian Standards (BIS) to undertake a study on the quality of the piped drinking water in the Country.
In the first phase, samples were drawn from various locations in Delhi and tested in the Laboratories against the standards laid down in the latest version of IS 10500: 2012 (Specifications for Drinking Water). In all 11 (eleven) samples were drawn from all over Delhi and all them failed to fully meet the requirements of the Standard. The parameters being tested were presence of chemicals, toxic substances, bacteriological tests and other physical tests. In particular, tests were conducted to detect the presence of ammonia, chloramines, barium, molybdenum and some other chemical compounds. In addition, tests were required to detect arsenic, boron and cadmium etc. The most stringent requirement was to detect the presence of viruses and coliform organisms.
In the second phase, samples were drawn from 20 (twenty) State Capitals and they were graded in order of compliance with the requirements of the Standard. Of these, only Mumbai was found to have the safest water supply, as all the 10 (ten) samples were found to be in full compliance. For the Cities of Hyderabad, Bhubaneshwar, Ranchi, Raipur, Amravati and Shimla, only a few samples did not meet all the requirements of the Standard. But in the remaining 13 (thirteen) State Capitals all the samples failed to fully meet the requirements. These Cities were Chandigarh, Thiruvananthapuram, Patna, Bhopal, Guwahati, Bengaluru, Gandhinagar, Lucknow, Jammu, Jaipur, Dehradun, Chennai and Kolkata in descending order of compliance.
In the third phase, samples will be drawn from the State Capitals of the North-East and some other smart Cities as identified by the Ministry of Consumer Affairs. Their results are expected by mid January 2020.
In the final phase, samples will be drawn from all district headquarters of the Country and their results are expected by 15th August 2020.
The exercise is meant to serve as a wake-up call to State Governments to ensure supply of quality potable water on tap for all households.
Indian Standard for Drinking Water IS-10500 (Drinking Water Specification)
The Bureau of Indian Standards (BIS) originally published the Indian standard for drinking water IS 10500 (Drinking Water-Specification) in the year 1983. Since then the standard has undergone three major revisions with the last one being carried out in the year 2012.
In this revision, a number of additional requirements for tests like ammonia, chloramines, barium, molybdenum, silver, sulfide, nickel, Polychlorinated biphenyls and trihalomethanes were incorporated into the standard.
The revision in 2012 also modified the requirements for color, turbidity, total hardness, free residual chlorine, iron, magnesium, mineral oil, boron, cadmium, total arsenic, lead, polynuclear aromatic hydrocarbons, pesticides as well as bacteriological requirements.
The standard also clearly lays down the requirements in terms of the acceptable limit and the permissible limit for each of the test parameters mentioned. All samples are required to comply with the acceptable limit and permissible limits are only applicable if an alternate source of drinking water is not available.
One of the most significant changes made to the standard in the year 2012 was the inclusion of virological requirements. The standard now clearly states that all samples taken from the distribution system including consumer premises should be free from viruses.
The standard also highlights that viruses are generally resistant to disinfectants and get detected by the presence of particulate inorganic matter in the water. Because the difference between the resistance of coliform organisms and of viruses to disinfection by oxidants increases with the increasing concentration of reducing components like organic matter it is not possible to assume that absence of available coliform organisms will ensure that water is free from active viruses.
Because of the serious health hazard posed by the presence of viruses in drinking water the standard further goes on to state that if viruses are detected the course should be determined and further immediate investigations must be carried out.