Should you get a septic inspection?
It is extremely important to have a proper, thorough, inspection of the septic system components if you are buying a home with a septic system. Unfortunately for many home buyers, the typical brief septic inspection tells you very little about the real state of the septic system. In my state, the tank is uncovered and viewed, and the scum level and depth is noted. A diagram is drawn indicating the location of the components. Septic inspections for the sale/purchase of a home is a limited visual inspection to determine the condition of the septic field and function of the sewage disposal system.

In some parts of the country, septic inspections are paid for by the sellers and in others, the buyers have to do their own inspections. As part of the home inspection process, in my part of the country sellers provide the septic certification. My state requires an inspection before a closing can occur. It does not require a functioning system, only a test. In other states, the inspection is optional. When the system is not functioning properly, the parties negotiate a correction acceptable to the parties involved.

The importance of a septic inspection.
If the house has a private septic system it should definitely be inspected by a professional septic contractor. An improperly functioning system can be a messy health hazard.  If you are already working with an agent, ask the agent for names of local, dependable home and septic inspection companies, then contact several companies or visit their company websites to learn what services are offered and to ask about rates. Sometimes yu can arrange to have a septic inspection company present on the same day as the home inspection which makes it easy to attend both inspections. If the septic inspection is scheduled on a different day from the home inspection, you may want to be there. In my state, a records kept of past inspections and pumpings, so you can check on the history of the system before the inspection.  Also, if you have a private well and a septic system it is be a good idea to have a water test as well as a septic inspection. In my state, most lenders will require a well test anyway.

The septic inspection should be completed and reported to the parties early in the negotiation process. Both the buyer and the lender have an interest in the operation of the existing system. Occasionally a repair or repacement is necessary. Banks usually won't lend unless the system is good or scheduled to be made good. In my state, a system can be repaired upto two years after title changes to a new owner. How the system is corrected and when is left up to the parties involved. My experience is that lenders will "hold back" an amount equal to one and a half times the estimate for the fix. Once it is fixed, the bill is paid from the held back funds and any excess is distributed according to the agreement between the parties.