A dosing tank has the primary function of supplying the wastewater from the pretreatment tank(s) to the aerobic treatment unit (ATU) in a uniform and consistent manner. Most single home aerobic septic systems do not utilize this tank due to the additional cost and the need for an additional pump and high water alarm but in larger or multiple residential systems it may be required but if not it is still recommended. If the wastewater has high and low flow periods or the potential for a flow rate that exceeds the flow capacity of the ATU then this tank will reduce the peak flow and deliver it to the ATU in an even and consistent manner so the ATU will not be overloaded. The dosing tank does this by storing the wastewater flow in the tank and pumping it to the ATU over a longer period at a rate that is an average of the flow over the longer period. This flow moderation allows the ATU to work more efficiently and operate at its maximum capacity. Here is a photograph of a dosing tank with just one opening in the center designed to allow access to service the pump inside.