You need a plumber to scope the lines as apart of due diligence even if sewer is cast iron all the way to the street.Usually they will charge xx number of dollars per toilet per unit.Galvanized rusts from the inside out so even if you replace all plumbing in the building you can have low water pressure from the galvanized main and also leakage into the ground running up the water bills.Engineer for the city water department should tell you for the area what the average usage of water is per number of tenants that typically occupy that square footage of space.

My tenant reported water heater leakage on 14th Feb.

Would you recommend an entire repair on the garage wall and roof or is it possible to just remove the mold and add some more coating to the roof to prevent further leakage?

Third bathroom from scratch in my basement which involved busting up the concrete floor, moving the main stack (and a cleanout  the front of the a semen while I was at it).

And water leakage with a curtain on the shower will trash that floor in no time.

I mentioned a special thanks to you in my new member intro as well.Anyways, Yes the landlord pays for water and based on preliminary numbers we received during the due diligence it seems there are some water leakages that need to be fixed.

I had no way of knowing if the smell was from sewer gas or from the leakage, but one wasnt wet anymore so I assumed it was gas.

Interior plumbing leaks..Has damaged been cause to the drywall over a leak?? Age

I check for signs of plumbing leakage in the kitchen and baths and do a visual inspection for any noticeable damage.  

Now if it involves cleaning out a sewer line or locating a pipe leakage inside a wall or underneath flooring, that's when a you call in the licensed professional.