Looking for help...Sell or Rent?

[Brad McCoy]

Back in 2005 the house just down the road from me went up for sale. It came with ~22 acres that butts up to our current residence. We were offered the residence first and bought it as is via FSBO. My mom ended up moving in and we have been renting it to her for less than our mortgage payment on the property (I know, you shouldn't go negative on a property but it is my mom). Anyway, she is now moving out and I have to decide if I want to sell the house or rent it out. The residence and acreage are on two separate tax id parcels so I would not have to survey the acreage off. I do plan on keeping the acreage regardless of what I decide.

Some of the numbers:  I bought the house and acreage for a total of $125,500.

I currently have an ARM which the rate is at 4.125%.

My monthly payment which includes T&I is $579.33

Balance is currently $48,368

The house is assessed at $91,700 for tax purposes

House sits on 2 acres

House is approximately 1,500 square feet, 3 bedrooms, 1 bath

This house is located in the country

The house is old (50+ yrs) and the septic is a conventional system.  I just had it pumped and it did pass inspection, however I know it's just a matter of time before it will have to be replaced.  It's grandfathered in as a conventional right now, but when it has to be replaced it will have to be a mound system.  I estimate it will cost $15-20K to replace.  

Do I rent the house out and replace the septic when needed or sell outright and let the septic be someone elses problem?  If I rent, how much rent can I expect?  So many questions.  I have been a landlord for 13yrs, but I feel like it doesn't really count because it was my mom renting from me (never had a missed payment ;).  Any help would be appreciated!!