Gravity Fed Rainwater Harvesting systems simply collect rainwater from the roof of the property and passes it through a filter which removes any leaves and twigs. Thereafter, the water is pumped into a sub-surface storage tank.
As the water settles in the storage tank, the heavier particles drop to the bottom of the tank.
The stored water is pumped to a Header Tank located in the loft. The Header Tank then uses its own gravity pressure to feed the water demands. The pressure provided by a Gravity Fed system is not enough to supply washing machines or dishwashers.
However the advantage of this system is that it is easier to install and requires less pump power, giving the pump a longer life expectancy.
Commercial Rainwater Harvesting systems work exactly the same way as domestic rainwater harvesting systems, with the exception that larger roof space means that they can collect more rainwater therefore can supply larger water needs.
Commercial rainwater harvesting systems are used principally for toilets and are typically only gravity fed systems. For those with large water needs, such as nurseries or farms gravity fed rainwater systems can offer significant savings.
Please note that underground storage of rainwater eliminates the growth of algae as the water can easily be filtered before entry thus also making it much cleaner.
Another advantage of underground storage is that you can have large amounts of storage without taking up room in your garden.