1, industrial pollution
In the past, most drinking water quality exceeded the standard in sensory and bacteriological indexes. Nowadays, due to industrial pollution, more and more drinking water quality chemical and even toxicological indicators exceed the standard. It is difficult to guarantee the quality and hygiene of drinking water for rural residents who directly drink surface water or shallow groundwater. Some rural areas are close to industrial areas. Wastewater discharged from factories directly enters villagers' drinking water sources through various channels, and harmful substances in factory exhaust gas also enter drinking water sources through various channels such as rainfall and direct precipitation.
2. Agricultural non-point source pollution
Non-point source pollution refers to the unreasonable use of chemical inputs such as pesticides and fertilizers in farmers' lives and agricultural production, as well as the random discharge of human and animal feces and garbage, which makes nutrients such as nitrogen and phosphorus and organic or inorganic pollutants such as pesticides penetrate into the surface or farmland, causing water pollution to rivers and lakes. Agricultural non-point source pollution has the characteristics of large influence range, many influencing factors, complex methods and difficult quantitative evaluation of intensity.