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[[Image:akkerman.jpg|thumb|right|300px|A women using her water storage tank in Guinnee-Bissaurainwater capture system from a small household. Photo: Paul Akkerman]]
Rainwater harvesting refers to structures like homes or schools, which catch rainwater and store it in underground or above-ground tanks for later use. Any suitable roof surface — tiles, metal sheets, plastics, but not grass or palm leaf — can be used to intercept the flow of rainwater in combination with gutters and downpipes (made from wood, bamboo, galvanized iron, or PVC) to provide a household with high-quality drinking water. A rainwater harvesting system might be a 500 cubic meter underground storage tank, serving a whole community, or it might be just a bucket, standing underneath a roof without a gutter. Rainwater harvesting systems have been used since antiquity, and examples abound in all the great civilizations throughout history.
====The EMAS filtration system ====
[[Image:Filter.jpg|thumb|right|250px300px|Filtering the water coming from the gutter.]]
The EMAS system for rainfall collection uses various EMAS technologies as well as simple tools to convert rainwater into usable drinking water. If roof rainwater is being used, it is collected through a regular gutter. To filter the water, at the bottom of the gutter, a pitcher or ferrocement tank is placed, with an outlet pipe. A synthetic cloth bag is attached to the rim of the pitcher using an iron ring or wire, which fits around the edge. The bag should be cleaned every 3 months.
