Dealing with joint water and sewer bills

[Michelle Tucker]

Seeking advice- We just started renting out a duplex and the tenants are responsible for utilities- Including water and sewer. There is no way to assign these accounts to the tenants directly so -the water and sewer will remain in our name - Any advice on how to appropriately charge back to the two tenants in a equitable fashion?

One tenant is a family of 5 in a 4 bed and one tenant is a single person in a 2 bed.

Appreciate any methodology that has worked for anyone with a similar situation? The prior owner used the duplex for her business so she had no precedent for this-

Thank you in advance!