How should I handle water bill?

[Jeremy Anan]

We acquired this MF property couple of months ago. It looks like the previous owner paid the water bill for all the tenants whether or not it was included in the lease agreement. We are now in the process of renewing the lease for a few tenants (the ones that are supposed to pay their own water bills). 

How should we handle the situation since they are now used to not paying their water bill. Should we just send them the water bill statement or should we attached to that an explanation to why they should now pay their portion of the water bill?

The property is located in MD and the water bill is would be divided by the number of tenants including the laundry unit. 

Thank you for your help.