The TRU-BEND is designed to maintain maximum water levels upstream of the weir thus allowing full usage of all the available upstream storage volume while not adversely affecting the overflow weir capacity in Combined Sewer Overflow (CSO) applications. The TRU-BEND’s unique and extensively tested design operates by only allowing any excess water in the system to reach the receiving stream but only after the design upstream water level is reached. This increases the tank and sewer storage volume and reduces the frequency and volume of overflow events, resulting in a decrease in water pollution. The TRU-BEND protects against backflow as it is normally in the closed position.