Abstract: Inflow of external water of a city into its drainage pipelines impacts the efficiency and energy cost in sewage treatment works, increasing the risk of overflow and environmental pollution. This study is aimed at constructing a water quality characteristic factor library for the drainage network of a typical city, Foshan, laying a technical basis for subsequent identification of external water infiltration. Through a comprehensive analysis of the functional areas of a typical region in the city, we identify and focus on five water categories－domestic sewage, industrial wastewater, agricultural water, river water, and rainwater. Their quality characteristics are determined through sampling and laboratory measurements we have conducted in this study. For the five categories, characteristic factors are total phosphorus and nitrogen, chemical oxygen demand and manganese, nitrate, dissolved organic carbon, and salinity, respectively.

Key words: drainage pipeline networks, various types of waters, water quality characteristic factors, external water infiltration