The introduction of modern sewage in the XIXth century was largely related to the invention of the modern wc. This device had undeniable health advantages, but a clear problem: the need for a water volume that, combined at the scale of large cities, can become relevant. According to New York’s PLANYC, some years ago that city was considering a new reservoir to cope with a rising water demand; the final solution was a wc renovation program, with model whose water demand was lower, as to eliminate the need for the new reservoir. On the other side, the disposal of used water also requires a costly infrastructure.

The problem is where you have no water pipes, a common situation in many countries. The Bill and Melinda Gates Foundation launched in 2011 the Reinvent the Toilet Challenge, aimed at designing a toilet with no water needs. The aims where:

–           Remove pathogens and recover resources as energy, clean water and nutrients

–           Operate without need for water, sewage or electricity grids

–           Cost less than 5 dollar cents a day to operate

–           Promote sustainable sewage services in poor urban environments

–           Become an aspirational next generation product that everyone will want to use in any nation.

The result has been a series of grants to varied institutions to develop prototypes. A wonderful idea for developing countries, a chance to reduce infrastructure and environmental impact in any country.