Check first of all that it is a septic tank it is all going into. I just bought two cottages and one sewage system empties into the gully besides the road 100 yards away and the other should discharge into the garden (open ended pipe on grass) except that the pipe is broken as it passes through the garage . The only thing to go into the septic tank are that which goes through you, French toilet paper, and allowed chemicals (read the label first)