I am looking to buy a home and had them come out and pump as well as inspect the septic tank before I commit to buy. The guy who pumped put the septic tank said that the tank is in good shape but could not tell me the shape of the field lines. He said he did notice that there were black marks on the walls of the septic tank that come from the septic tank being at different levels but other than that all looked good. I want to know what would cause the fluctuation of the level in the tank? Is or could that be a sign of anything bad? I dont know much about septic tanks and need some type of input on what would cause this. I must also say that one of the tanks tops were off when we got there and it had rained for 4 to 5 days before the inspection was done. The home is a foreclosure and I have clue on how long it has set empty. Before pumping the system I did have a home inspection and he flushed the toilets and ran water at all faucets and nothing drained or flushed slow nor were there any gurgling while test them systems. Standing outside there was no odors or sogginess around septic tank or field lines. Not sure if it matters or helps but the home is in central east Alabama.