Washer/dryer combo with cesspool

[Frank Rizzo]

Hi, 

I just closed on a 100 year old primary residence for my family and I, the property includes 2 rental cottages that will pay most of the mortgage when rented. To get top dollar I would have to install a washer/ dryer. The problem is the plumbing system, they both have their own 500 gallon (or less) cesspools according to the inspection. (I am going to have to install septic at some point...but not today.) My question is, will a 500 gall cesspool be able to handle  a small energy efficient washer/dryer to a studio-1bd (max 2 occupants)? Thank in advance for the feedback