Ecological Damage:
Sewage-contaminated water causes eutrophication, which is the increase in concentration of chemical elements required for life. The nitrates, phosphates, and organic matter found in human waste serves as a food for algae and bacteria. This causes these organisms to overpopulate to the point where they use up most of the dissolved oxygen that is naturally found in water, making it difficult for other organisms in this aquatic environment to live. The bacteria are basically strangling the other organisms. Some of the organisms that do overpopulate from this can also be disease-causing microorganisms. Phosphates are also found in soaps and detergents, but there are other household products that we use everyday that can be toxic to many animals and humans if they are dumped directly into a water body.