What if you turn on water and it goes everywhere.

And I will state different jurisdictions have different rules, processes, expectations, etc.In my area you are required to have a permit to swap a water heater.

Quote from @Aaron Wolman: I would call the companies (gas/water/electric) to get estimates, or an estimator out there.

City water with one main at the street and how will they bill. 

Did nobody ever stop and say "oh, hey, maybe we should keep water pumps going because, ya know, no electricity no water pumping, NO WATER". 

It appears to be a means to an end and the path of least resistance (somewhat related to number 1).

The meters are read electronically with 3g and you get great reporting in their water scope platform.

I used to live in the city and the taxes and water bills are nightmares.

Resist the urge to oversell yourself and your experience.

If the water bill is $100 a month, increase the price by 20% (or whatever you decide is fair) to compensate you for the time required to split and bill and to cover additional use when tenants squander the utility.