Diffuse water pollution is caused by various sources, which are often hard to identify. Individual sources may be relatively small but the combined effect of numerous sources can be damaging. Diffuse pollution has a greater impact on the water environment than any other source of pollution.

In rural areas sources of diffuse water pollution include- run off from agricultural land containing substances including pest control products animal medicines slurry sewage sludge and manure run off and leading from contaminated land slit and sur from mining