No matter how much water is diverted, it is necessary to build a regulating pool, which is a structure used to regulate the import and export flow. In the sewage treatment plant, in order to make the pipes and structures work normally and not be affected by the peak flow or concentration change of wastewater, it is generally necessary to set up a regulating tank in front of the sewage treatment facilities.

The function of the regulating tank is to make the quality and quantity uniform. Generally speaking, functions such as precipitation, mixing, dosing, neutralization and pre-acidification can also be considered.