To me, there's only two reasons you should even consider charging a tenant for a water leak:  1) They intentionally caused the leak through some sort of negligent act or misuse of equipment, or 2) They didn't cause the leak but they noticed a readily apparent leak (and you can prove this) and then failed to notify you of this leak and that failure to notify you allowed the leak to become worse and cause additional damage above/beyond what it would have had they notified you right away and allowed you the opportunity to deal with it immediately.For example, my lease has a clause that states, in part: "Tenant shall immediately notify Landlord, in writing, of any problem, malfunction or damage.

I am currently studying finance and am in love with architecture.

You should take to multiple lenders and see how the approach differs between banks and what is consistent between the banksAlso - Most banks will require an executed lease on the "old" primary residence turned rental to prove it's rented out or going to be rented out by a certain date before you can close on your new 2nd primary residence loan. 

It's important you study the law and prepare for this because it's likely to continue happening to you. 

This is your budget of income and expenses and how you will run the asset.For Market information, what information are you using to prove out this deal is a good one?

I spent years studying before I finally pulled the plug.

That would be the FORMER owner.Assuming he can prove this bill he received was due to your tenants not paying their bill (as opposed to being from one of his other properties), how is it right that he should have to pay it?

I imagine the possibility of building some large communal areas (living, dining, kitchen, work out, study/office, playroom) which will be central to some clusters of 2-3 rooms for sleep mainly.

He just may need to prove that to the lender, which is what he is asking help with. 

When I finish school in 2 years my intention is to do this after I get a solid job, similar to your situation..I'm looking to do this in Bradenton, Florida though, I will keep reading and studying but eventually will pull the trigger when the time is right