I'm curious if anyone has experience splitting water in an apartment complex. I'm looking to get an 11 unit and currently the utilities run about 25k per year. I'm wondering how much it might be to split the water and pass that along to the tenant. It is an old building so I'm guessing it'll be more than normal, and may want to get a plumber's consultation, but curious to hear people's thoughts if they've gone through this process, and possible hurdles they had or things they wish they would have known.
First, see if there are any local laws governing this. (This is called RUBS for Ratio (or Resident) Utility Billing System). Most laws prevent you from making a profit on RUBS. Also, most laws specify some sort of percentage that must be applied to common area usage that cannot be rebilled.
Once you know that, a simple spreadsheet suffices. Typically costs are allocated based on size of unit and number of people. So, for example, you might charge more to Unit A if there is one more person living there, even if it is identical to Unit B.
RUBS can be a little of a challenge because of the delay from usage to billing and the potential to violate a local ordinance. At our apartment, we decided to go with a flat fee for utilities based on unit size and # of people. Since it is communicated as a standard up-front fee, you don't have all the pitfalls of a true RUBS system.