With the official implementation of China’s HJ 212-2025 Technical Requirements for Data Transmission of Pollutant Automatic Monitoring System and the upcoming enforcement of the Ecological Environment Code, stricter supervision is being carried out on wastewater discharge monitoring. Regulators have raised higher standards for online water quality instruments used at wastewater outlets, including pH, dissolved oxygen and conductivity sensors. Factories in chemical, pharmaceutical, food & beverage industries, together with industrial wastewater treatment plants, are now entering a critical period to evaluate and upgrade their monitoring systems.