Underground rainwater harvesting
Where the roof is catching the rain as in the previous measure, this measure stores the water in an underground tank. Besides storing water to be used in dry spells without rain, it offers a way in which water is kept cool in a warm environment. The harvested water runs from the roof to the tank through gutters and pipes.
A hole (3 m wide, 2 m deep) is excavated to build the tank. The walls are constructed with concrete bricks and mortar, followed by a mortar lining. The base is also lined with mortar. To reduce losses through evaporation, the tank is sealed – except for the lid. Again, the lid should be large enough to fit a person for occasional maintenance and cleaning.
