Abstract: A waste water filtration tank receives waste water under hydrostatic pressure. The tank collects solids using a filter screen. When the screen becomes clogged with collected solids, liquid is forced into a float chamber which contains a float. As waste water collects in the float chamber, the float rises, as do a beam member and a pair of rod members to which the float is attached. When the float reaches a predetermined level, cams contained on the rising rod members act on spring-loaded latches, opening the latches and permitting a spring loaded sleeve and reservoir gate to rise, opening the reservoir outlet. Accumulated solids are then drained from the reservoir and the backwash from the screen chamber also clears the clogged screen.