Is Septic Field testing required for Sale in order for financing?

[Timothy Hillyer]

My father is preparing to sell his home. The house is on its own septic field. The septic field was originally installed in the '80s. My father bought the house in 2002. The septic field has never been tested; he did not have it tested before he bought the property.  When he goes to sell the house, what can he expect?  If there is a home inspection and the inspection recommends having the septic field tested, can he refuse and say "as is where is"?  Will an appraiser call out the septic field and require it be tested and not allow financing until after their is a test of the septic field?  Is my father legally required to have it tested to ensure that it is working properly? Anyone with any experience with this?  Thanks for the help.