here in iowa they just enacted new septic system regulations.so if the property has one when you go to sell it has to be up to code or no sale.if you are selling you have to have the tank sucked out and then the sanitarian of the county will come out and test to see if it is a working system.i don't know if they do the perc test on an existing system but you will need to for a new system.as for my soil type here i have to have 100 linear feet of laterals per bedroom,not bathrooms.also the bottom of the laterals have to be at least 36 inchs above the bottom of the ditch.so because of this my system has a pump pit that the liquid flows into,when the level gets high enough the pump pumps it out thru the laterals.also the tank has to be x number of feet from the house and the laterals have to be x amount of feet from property lines.your best bet would be to find a plumber in the area that does septic systems and see what the specific requirements are.around here you can get the whole system replaced for 6-8k.