law: 218. Sewage and rain water drains to be distinct.
  Wherever it is provided in this Chapter that steps shall or may be taken for the effectual drainage of any premises, it shall be competent to the Chief Executive Officer to require that there shall be one drain for filth and polluted water and an entirely distinct drain for rain water and unpolluted sub-soil water or both rain water and unpolluted sub-soil water, each emptying into separate cantonment drains or other suitable places.