In this situation, you don’t really have too many options. Since the utilities are already included in the rent, there is no legal way to have the tenants pay for the excess costs of the hydro/water. The only way that would be permissible is if the tenants agree to start paying for the utilities. However, even if they do agree to start paying for the utilities now, you would have to reduce the rent to compensate for the removal of a service that was previously included in the rent.