Septic tanks should be pumped every 3-5 years, depending on the size of tank, the amount of solids entering the tank, and the users’ habits. The tank should be pumped if the scum and sludge layer exceed 49% of the volume of the first compartment of the tank or if the sludge on the bottom of the tank is within 12 inches of the bottom of the sanitary tee. (visit our blog for more info)