In the midst of submetering apartment - need help on lease change

[Jonathan Beasley]

Hey BP Studs and Studettes. I'm pulling the trigger to submeter water and sanitation at an apartment. It is a 6 units, with 3 of the leases up in the next 30days. I have a 4th renter that is very behind in rent, and so I may ask them to agree to pay their own water or just proceed to eviction. 2 questions. 

1. How can I get the last 2 tenants to sign off on paying utilities mid-lease? Or can I do that at all?

2. What is some good "language" to put in the new leases to account for paying their own water and trash??

Thanks!!!!