We manage several hundred multifamily units in and around Columbus, and have tried every different way to bill water - included in rent, split among tenants, and sub-metered. Our recommendation is sub-metering, for the following reasons:
-You will get monthly reads instead of quarterly, so any leaks or other abnormal usage can be addressed faster (this one benefit alone could save you thousands on a water bill). Even when vacant you'll be able to see what's going on with water usage. Lifesaver in winter especially.
-Because it's more fair for the tenants (they are billed for their exact usage), they are more likely to renew their lease and/or just behave better.
-It's essentially free for landlords (at least with Guardian) once it's set up, because the cost of the service is included in the tenant's monthly water bill.
-Using the city water bill, it's an issue at move-in and move-out to prorate usage since the tenancy won't line up with the billing periods. With submetering, you can provide readings at move-in and move-out and thus bill the tenants precisely for their usage.
Many MF properties in Columbus already have submeters, take a careful look and you may find old submeters not hooked up and either inoperable or simply not in use. Get them up and running; you'll be happy you did.