Rainwater harvesting

Rainwater harvesting for human use requires filtration and purification. Rain water can be contaminated with algae, air pollution, bird excrement, leaves, sand and dust. It should be tested in a laboratory in order to determine what equipment is most suitable for the area.

First rain will hit the conveyance system (the rain collector), which must be protected from any incoming foreign matter, in order to reduce maintenance and extend life of filtration, purification and pump systems. Particulates will bypass the conveyance system and enter the tank, here they must be screened into a sediment. The sediment is best kept at the bottom of the tank and left undisturbed. A floating filter is effective for extracting water from the middle of the tank and leaving the sediment at the bottom. Filtration removes debris from the water, nearly all systems use multiple filters. Filters include screen filters, paper filters, carbon and charcoal filters, they are measured in microns, a micron is 1/100th of a human hair, or 1/25,000th of an inch. The type of filter used must be decided on by what the filter removes and the quality of the water. Filters will not eliminate all harmful substances in the water, so next comes purification/ disinfection. This includes chlorinization, ozonization, ultraviolet light and membrane filtration.

Then the water can enter a pump, to be ready for consumption or cleaning.