Explain briefly, how rainwater harvesting is done from open spaces around the buildings in city areas.

In the open spaces around the buildings in a city percolation pits, covered with concrete slabs having holes in them, are constructed and connected to a recharge well through a pipe. The rainwater which falls in the open spaces goes into the percolation pit through the holes in its cover. This rainwater, after filtration in percolation pit, enters the recharge well through the outlet pipe and gradually penetrates into the soil.