law: Water (Prevention and Control of Pollution) Act, 1974
  45. Enhanced Penalty after Previous Conviction.
  
  If any person who has been convicted of any
  
  offence under section 24 or section 25 or section 26 is again found guilty of
  
  an offence involving a contravention of the same proviso, he shall, on the
  
  second and on every subsequent conviction be punishable with imprisonment for a
  
  term which shall not be less than two years but which extend to seven years and
  
  with fine :
  Provided that for the purpose of this section no
  
  cognizance shall be taken of any conviction made more than two years before the
  
  commission of the offence which is being punished