Rainwater harvesting is an uncomplicated and extremely functional practice to save water. Beginning harvesting of rainwater in your school requires small steps to be implemented carefully. They are:

1. Find a little territory in the premises, where you can dig a ditch of 4ft x 4ft to a profundity of 8 to 9ft.  
2. Top it off with 40mm stones, up to three feet from the bottom.  
3. Top off next 33% with 20MM stones. These two layers enable the water to stream effectively into the lower ground.  
4. Last upper segment must be loaded up with coarse sand (the sand left after screening- fine sand). This layer SUCKS up water at a QUICKER rate.  
5. Redirect rainwater gathered on your rooftop top to this pit with funnels of appropriate size (4 to 5 inch in diameter).  

That's it in a nutshell. The rainwater collecting pit is prepared. It will be a delight to WATCH the water coursing through the pipe getting retained at a quick rate. Gradually the water table near your water siphon keeps coming up.

Preservation: Once in a year, evacuate the upper SEDIMENT layer of around 3-4 mm that happens to be a result of the water stream. Else, the water assimilation rate may go down.