Basically I have a rental that is 2700 sq feet with pool and landscaping and right now is using $50/mo for water and sewer (higher in the summer) so I budget $50 for any rental smaller than this with less water usage just to make sure I am not undershooting the value.Same for Electricity and same for gas: Call and ask or ask the owner/tenant what the average bill is.Repairs- I budget 5-10% of purchase price, but only as personal preference, you will figure out what you need as you go along.Vacancy-this is more than most would do, but I collected demographic data on all zip codes in Tucson so I knew the vacancies, employment sectors, house hold size, schools etc of my target areas.

The broad context of this analysis is straightforward: an economy based on ever-rising consumption falters when real household incomes stagnate or decline.

Seems you have one property and what will soon be two households.

Lynn says this is household money.

Now, there is a large market for working class folks, who make around $30-45k gross household income that have decent stable jobs that have around 550-640 credit scores that need housing just the same.

How much is your monthly household income?  

Sure its a little slower, but when you have a vacancy in the winter you learn that many of the reasons for household moves (divorce, new job) happen any time of year, even in Milwaukee.  

What is the local economy (is it broad based or based on one sector) What is the median household income?

I am looking at going into the single family household rental business here in Michigan.

The following was found in a google search:When septic systems are properly designed, constructed, and maintained, they effectively reduce or eliminate most human health or environmental threats posed by pollutants in household wastewater.