Residential septic tank with seams above sewage line and residential septic tank with stepped ribs

Abstract

A water-tight fiberglass septic tank is strong enough to withstand live loads. The fiberglass septic tank is preferably designed with integral ribs to for structural strength. In one preferred embodiment, the tank is made in two unequal halves. The lower half comprises the major portion of the tank and includes a bottom, two endwalls and two sidewalls. The upper half comprises a cover. This arrangement allows the horizontal seam to be placed above the internal waterline, thereby protecting the seam from exposure to sewage. At least one of the endwalls includes a raised top portion that allows a pipe to be located near the top of the lower portion without passing through the seam between the upper and lower portions of the tank. The endwalls are also curved to allow for angled inlet and outlet pipe connections. The ribs are preferably internal and hollow. The lower portion of the tank is also preferably flat bottomed. A provision has been made for a self-locating baffle if required. In another preferred embodiment, a cylindrical male molded tank is created on a mandrel. The tank circumference is stepped, which both provides for built-in stepped ribs and eases removal of the tank from the mandrel. In preferred embodiments of the tank, a baffle is located at the position of a stepped rib so that the stepped rib supports the baffle.