This chapter provides information on flow equalization processes used to pretreat industrial waste streams, considers the effects of each process, and provides basic design criteria for each. Flow equalization usually involves constructing large basins to collect and store wastewater flow, from which wastewater is pumped to the treatment plant at a constant rate. The alternating-flow diversion system collects the total flow of an effluent for a time period while a second basin is discharging. The intermittent-flow diversion system diverts significant variance in stream parameters to an equalization basin for short durations. The completely mixed, combined-flow system completely mixes multiple flows combined at the front end of the facility. The completely mixed, fixed-flow system is a large, completely mixed, holding basin located before the wastewater facility that levels variations of the influent stream parameters and provides a constant discharge. A primary consideration is the effect of the effluent on downstream facilities.