Abstract: A method and apparatus for diurnally storing and releasing municipal sewage in its conveyance network of sewers and interceptor piping to affect a reduction in peak energy demand and on-peak energy usage at the wastewater treatment plant, and, to reduce peak loadings to wastewater treatment plant clarifiers, aeration basins, channels and pumps, thereby improving plant performance and extending the wastewater treatment plant capacity. Utilization of the existing sewer system provides a way to obtain cost effective electrical cost reductions, flow equalization capacity, or an optimized combination thereof. With the disclosed invention it is possible to equalize wastewater flows, or alternatively to shift flow peaks from the on-peak electric rate periods to the off-peak electric rate periods providing less equalization.