Many times trough the years in many places in the world there were dry periods with no rain that do a lot of damage to the plants and people too. So, people have decided to collect and use when they need the rain water in organized system. The rainwater from the streets is polluted so this system also offers a filtration of it and safe collecting and keeping.  There is a recharge pit and whole process that makes this working. More, in the link bellow.

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