I looked at an 1,100 sq ft house a few years ago where a thief stole the copper pipes and let the water run, flooding the house. 

There are a number of reasons for this, chief among them, the water and sewer systems are built for a certain population, so are the schools, roads etc.

Check the application against all of your other screening criteria before entering the murky waters of a service animal. 

Then house drainage, does the water run away from the house or towards it, any foundation cracks, shifts, issues? 

I have an opportunity to get a SFR for 45k that is in a rough area but newly renovated with new hvac, water heater, and roof. rent should be 750 per month, taxes 650, ins 900. assuming 35% for capex and repairs and 10% for PM. assuming 8% vacancy factor and 5% leasing.

Remember the cost for connecting water/sewer or maybe in your area it is well and septic.Great job.

I don't have anything listed for water and sewer or garbage, because I am returning that to the tenants with a flat fee.

Owner is currently paying water, sewer and garbage, but I excluded those expenses and instead will make that a fee for the tenants to pay and added it under other income.

You must be thinking that I'm saying something I am not saying, because what I'm saying is purely common sense, no extensive scouring of data necessary. 

Obviously everything here is purely my opinion and speculation.