In order to reduce the amount of wastewater, we should first focus more on the source of wastewater generation. If water recycling or repeated use can be considered to improve the water recycling rate and minimize the amount of external drainage. In foreign countries, the water recycling rate of some advanced enterprises has reached over 96%, while the water recycling rate of Shanghai production enterprises is still at a relatively low level of 20-30%, and there is still great potential to be explored. Improving the recycling rate of production water can not only reduce environmental pollution, but also reduce the amount of fresh water needed for replenishment, which can to some extent alleviate the increasingly tense water resource problem. When treating wastewater, the recycling of treated effluent should also be considered as much as possible.