common occurance really.. when you bought it did you get an appraisal and compare the apprasiers sq ft assessor.

As a general rule, all of the national sources have aged data as compared to you going to the local county offices and abstracting the fresh information yourself.  

Good to see the number of sales for 2015 is up compared to 2014. 

Compare that to the county that I live in (near SF, population of 1.6M) where there are only a few hundred homes for sale, Indy looks appealing and yet a very dangerous investment.

I'd like to expand it a bit further and point out housing prices across the nation being high (see case shiller inflation adjusted home index and compare current level to historic norm).  

(Incidentally, dividing purchase price by gross rent - the inverse of what you were doing - is known as Gross Rent Multiplier or GRM and is very similar to looking at per-unit cost - an extremely rough way of comparing properties.)

My decision is easy compared to yours.  

I would also include how this compare to previous water bills and the two people who found no leaks including their representative.

Thanks @Brent Coombs, yes I didn't think of changing the %down just to change the cash flow. at the end we are trying to keep some things constant as we compare different deals. 

The tricky part is to measure the water and compare it to the meter dials.