I have a faulty septic tank. The tank is quite large, approx. 5 x 2 x 1.5, but fills rapidly - in the wet it needs to be pumped out often, sometimes every two weeks, the dry considerably slower. Obviously, ground water must be entering. When operating normally a septic tank should not fill up and, as a guideline, should only need pumping out probably once every 5 years if that. This is a very large septic tank (15 cubic metres, most tanks are only a quarter of this size) and should take a while to fill up. Check once more...https://blog.looglebiz.com