Look closely at your future water and more specifically sewer expenses.

Most municipalities have been deficient in maintaing their utility infrastructure. The fiscal irresponsibilty requires extraordinary increases in future water & sewer charges, often far exceeding any CPI adjustments you may consider in your pro-forma. Often the "approved" yearly increases are scheduled years in advance, so dig into what your future utilities will cost.

Better yet sub-meter, take the utilities out of your rental equation.

“We’re here to answer your sub-metering questions”