The permissible limits for dissolved solids per litre of water as specified in IS : 456-2000 are as under. Organic solids not more than 200 mg/litre, inorganic solids not more than 3000 mg/litre, sulphate as SO‌3 not more than 400 mg/litre and chlorides not more than 2000 mg/litre. According to standards of WHO only 500 mg of dissolved solids are allowed.