Just a larger view on this issue. I don't consider animal or treated human waste going into watercourses as pollution because they're organically based and therefore naturally break down in the soil over time which is beneficial to many plants and other organisms. Some fish and crustaceans actually thrive on it. There are far more inorganic pollutants getting into watercourses by whatever means which cause far more harm.
As a keen angler i can assure you that animal waste including the human animal is a serious pollutant even after treatment !
In my home town the River Wey was healthy and natural above the water treatment plant but this changed below the outfall . Green waterplants flourished upstream as did insects and fish while downstream the riverbed was lifeless apart from a carpet of slimy brown algae.
Untreated animal waste is much more dangerous deoxygenating water and killing all aquatic creatures.
Well diluted waste water may be ok but todays need for water abstraction means there is often much more effluent than clean water in a stream or river.
