In order to efficiently treat the ever increasing volumes of sewage that mankind produces, a change has to come. The gravity water toilet that has been around for centuries would have been banned if it was invented today, because it uses too much of one our most precious resources - water - and produces too much sewage.
Treating and pumping all the fresh water needed for toilet flushing consumes enormous amounts of energy, in many cases leaving a huge carbon footprint at the power plants that supply that energy.
Huge treatment facilities
At the other end of the pipe, energy-consuming pumps are also needed to move the sewage to treatment plants. These plants do not only use massive amounts of energy to treat a mix of greywater (household wastewater) and blackwater (sewage); their huge size also take up a lot of land that otherwise could have been used for more useful purposes.
Sewage handling is also a risk to inland waters, as spills wash out nutrients that cause harmful accumulation in such waters. Bacteria feeding on decomposing sewage steal dissolved oxygen from the water, suffocating other aquatic life.