11. Quality standards of water for drinking, cooking and bathing

Potability Standards: The most critical need for hygienic living is that of potable water i.e. water satisfactory for cooking and drinking. Standards for potable water the world over are largely reflected in the WHO standards for the same, which the CMWSSB has also accepted. The WHO recommends two standards for potability: i) Ideal standard with minimum levels of dissolved salts and minerals and ii) Practical standard with permissible (maximum) levels of dissolved salts and minerals. These are : Parameter Highest desirable Maximum permissible pH 7.0 - 8.5 6.5 - 9.2 Total dissolved solids 500 1500 Calcium (Ca) 75 200 Magnesium (Mg) 30 150 Sulphate (SO4) 200 400 Chloride (Cl) 200 600 Iron (Fe) 0.1 1.0 All figures except pH are in ppm (parts per million). Bathing Water Standards: Water for bathing purposes is the next critical need to be met for hygienic living after meeting the potable needs. Unfortunately, however, no published quality standards are separately available for assessing which water can be considered satisfactory for bathing purposes. While logically, the quality of water needed for bathing and washing purposes need not meet the stringent standards for cooking and drinking, municipal authorities the world over have chosen invariably to supply only water of potable quality to meet all the needs of the public. This is not merely because of the high cost of providing a second system of piped water requiring thousands of kilometers of piping to be installed and maintained. There are two serious hazards involved in such dual supply: (a) Users may consume the wrong quality out of ignorance, and (b) Cross-connection of the piping even if inadvertently made, may result in serious health hazards due to contamination of the potable water.