What are three specific examples of ...?

Question

the negative impact from water pollution and sewage

Answer 1

Oder.

Illness.

Death.

Answer 2

I know that sewage/eutrophication can cause algal blooms which then die (as there are too many) and clog up waterways. They can also release toxins into the waters and kill other animals, use up the oxygen in the water and again kill other animals.

Sewage also releases many bacteria into the water eg E.coli, which can spread.  I guess chloera and typhoid are the major ones people look out too. I know of someone who was walking in water nearby to a sewage outlet (isolated area and small amount of raw sewage) but she had a cut on her leg and it was treated very seriously by drs who were worried about infections she could pick up (via the wound).