Originally Posted by jdmorton
PS: CFB hit the nail on the head - if the previous owner really did not know that the house had a septic system, you have no idea of its status without a good inspection.
Even a good inspection has definite limitations. Most such inspections are quite limited in the amount of useful information they provide. The only reason they are done at all is to satisfy the lender's need to have some type of paperwork in their files regarding the general suitability of the system, to satisfy the demands of secondary mortgage market investors. The inspection does not protect you. In fact, it does very little to protect anything except a continuous income stream for local septic pumpers. In many areas the inspection itself is conducted by a firm whose primary business (and competence) is simply the pumping out of septic tanks. They generally will pump out the tank and then observe whether there is any backflow from the drainfield into the tank and that wastewater finds its way to the tank when a water using device is used. All this does is indicate that the system "appeared" to be functioning on the day of the inspection, nothing more. What this type of inspection will not tell you:
1. That the system is properly sized for the house you are considering purchasing. Drainfields are usually designed based on the number of bedrooms in the property to be served.(considered to be an indication of maximum probable occupancy and therefore water usage). It is not unheard of for a drainfield to be permitted and constructed for a 2 bedroom house only to have more bedrooms added prior to resale.
2. That the system will function properly all year round, not just on the day the inspection was done. A totally failed drainfield will appear to function normally, if it is unloaded (not used) for a period of time. If there is going to be a problem, it will occur when the system is being loaded continuously. Also, wet weather tends to aggravate the proper functioning of a marginal drainfield.
3. The maintenance history for the drainfield. Depending on the building occupancy, most septic tanks should be pumped out every 3-5 years to prevent the accumulation of undigested solids from moving into and clogging your drain lines.
4. Whether the drainfield is even legal. Design and construction of drainfields is regulated on a state by state basis and administered by local health department personnel. That does not prevent people from illegally constructing their own field which may or may not be properly designed and installed.
You must depend on your own due diligence if you are to insure that the septic and drainfield will not be an expensive problem for you in the future. Whoever inspects the system, find out exactly what they are going to do and ask tough questions. Contact the local health dept authorities yourself and verify the age of the system, that it was properly installed and what the design loading was. Ask the owners for proof that the system has been maintained. If you do not get good answers to your inquiries, consider hiring and engineer or soil scientist to represent your interests. If the house is not terribly old, has been continuously occupied and the system has been maintained, there is proabably nothing to get overly concerned about. Just go in with your eyes open.