What are the different types of rainwater harvesting systems?

Depending on the target catchment areas, there are many possible configurations and degrees of complexity to a rainwater harvesting system. Based on how the rainwater is pumped, it can be divided into the following categories:

• Direct Pumped
• Indirect Pumped
• Indirect Gravity
• Direct Gravity

Common Types of Rainwater Harvesting Systems

• Water Butt- This is one the most basic form of rainwater harvesting where the water collects in the container from the drain pipes and/or natural rainfall. It is usually used for gardening purposes.
• Direct-Pumped
  • Submersible - This type of rainwater harvesting systems is most commonly used for domestic purposes. The pump is located within the underground tank and harvested water is simply pumped directly to the WCs or other appliances.
  • Suction - This type of rainwater harvesting systems is located within a control unit within the establishment(e.g. utility room). The unit also deals with the backup from mains water supply, so there is no need to send mains water down to the tank.
• Indirect Gravity - This type of rainwater harvesting system first pumps the harvested rainwater to a high level tank (header tank) and then allowed to supply the outlets by gravity alone. With this arrangement, the pump only has to work when the header tank needs filling.
• Indirect Pumped - This type of rainwater harvesting system first pumps the harvested rainwater to a tank. This tank can be at any level in the building, as it does not rely on gravity to supply the outlets. Instead a booster pump set is used to provide a pressurized supply. This system employs the benefit of not having to feed mains back-up water to the underground tank, whilst also offering great flexibility as the booster pumps can be tailored to suit the flow and pressure requirements of the building.
• Gravity Only - In some situations It may be possible to have a system that functions purely through gravity. This type of rainwater harvesting system is only ever possible where the storage tank can be located below the level of the gutters, yet higher that the outlets that it will supply. Only the power of gravity is needed to feed collected and filtered water to various parts of the home for use, so it is an ultra-energy efficient option.