In addition to sewage, nonpoint source pollution such as agricultural runoff is a significant source of pollution in some parts of the world, along with urban stormwater runoff and chemical wastes dumped by industries and governments.
Ademais das augas residuais, fontes de contaminación difusas como as escorreduras agrícolas son unha fonte significativa de contaminación nalgunhas partes do mundo, xunto coas procedentes da auga das chuvias e tormentas urbanas e o lixo químico vertido polas industrias e gobernos.