The ancient canals are highly efficient thanks to porous rock below.
High in the Andean region of Peru, ancient Peruvians stored water in ancient canals dating back to the seventh century. In modern Peru, rural farmers are restoring them - and revitalising their water supplies.
The reason for the canals' efficiency at filtering water has to do with the make-up of the ground beneath them. Porous, rocky areas act as a sponge, allowing water to resurface within months or even weeks further down the mountain.
A non-governmental agency, CONDESAN, has helped farmers restore one of approximately 10 canals in the region.
Al Jazeera's Maria Sanchez reports from Huamantanga, Peru.
Source: Al Jazeera