The Chief Executive Officer may cause any or all of the cantonment drains to empty into, and all sewage to be collected of at, such place or places as he considers suitable:
     Provided that no place which has not been before the commencement of this Act used for any of the purposes specified in this section shall, after such commencement be used there for without the approval of the Board:
     Provided further that on and after such date as may be appointed by the Central Government in this behalf no sewage shall be discharged into any water course until it has been so treated as not to affect prejudicially the purity and quality of the water into which it is discharged.