Definition characters description and diffusion
Cisterns connected with each other through a network of open-air channels and tunnels collect rainwater and form a water decantation and filtration device by means of spillways on the sledges of the cisterns. Rainwater cannot be stored over long time because of the narrow mouths of the cisterns, but it is a water reserve for periods following rainfalls.
General characters description and diffusion
This system of water collection is still in use in some areas in Africa, where, after rainfalls, the mouths of the cisterns are covered with mats made of vegetable material which allow water to be stored over longer periods. All over the Murgia plateau, in the south of Italy, underground connected cavities are dug out of the limestone to collect water from the slope by means of a network of underground channels. The cavieties connected with each other are crossed by meteoric water flows. The underground structure enables on one hand to supply a larger quantity of water and on the other hand it does not allow water to be wasted by evaporation. The inside walls of cisterns are perfectly insulated by means of plaster made out of lime and shards (coccio pesto). The ancient technique of coccio pesto, dating back Middle Age, allowed water harvested into cisterns to be stored over a longer period.
Advantages and sustainability
Excess water from heavy rainfalls are trapped in these cisterns which in turn protect the water from natural processes such as evaporation.