Eutrophication is a phenomenon derived from the increase in the concentration of nutrients such as nitrogen or phosphorus in the ecosystem. In aquatic ecosystems, this leads to a great proliferation of algae and other plants that do not let the sunlight penetrate the bottom. As a final effect, the oxygen under the water is consumed and the fish and the rest of underwater flora and fauna dies. As a result, the water and the river or the lake per se cannot be utilized for the majority of uses.

The phosphates and other pollutants that we throw away through the wastepipe complicate the functioning of the sewage treatment plant. The simpler we make things, the easier and the cheaper (regarding to money and resources) they will be.