law: 12. Enhancement of rent on restoration of water-supply.-
  If a water-supply increasing the value of such holding is afterwards restored to the said land, the rent of the tenant may be enhanced in respect of the increased value of such land due to the restored water-supply, to an amount not exceeding that at which it stood immediately before the abatement.
  Such enhancement shall be on account only of the restored water-supply, and shall not affect the liability of the tenant to enhancement of rent on any other grounds.