1. You are deficient in providing details in your queiry.
2. In which city your property is situated?
3. Is the any provision of water meter required as per rule of your local Municipal corporation?
4. You can install a water meter in your water supply to the tenant to record the monthly consumption.
5. This way you shall have the recorded evidence of your tenant's spending huge amount of water much beyond the expected level.
6. Thereafter you can write to your tenant to restrict their water consumption to a particular level of the water meter or pay for the expenses you shall have to incur for drawing the additional amount of water he is over spending in a month.