If a septic tank is operating properly, solids are retained and take up increasingly more volume. Eventually, they must be removed.If there is little accumulation of solids, either the household has limited usage or there is a problem causing solids to pass through the tank. When there is little clear zone left, proper solids separation will no longer occur, detention time for settling is further reduced, and solids will wash out of the tank, eventually clogging the soil treatment area or downstream component and then causing system failure.Research on solids accumulation shows the interval between pumping depends on tank size,
