How to separate utilities between tenants??? Need help please

[Lee V.]

I own a triplex. I live in the main house up front which has its own water and electric meter. 

I have two small homes in the back that share a water and electric meter. How do I handle utilities for these homes since they share a meter?? Should I ask the two tenants to split the bills down the middle?? Who's name would the utilities be under? Do I put it in my name and have tenants pay me for the utilities? I'm so confused. 

Located in Houston tx