Rainwater Harvesting Systems

A rainwater harvesting system has six main functions:

  To collect rainwater from the roof and gutters
  Transport the water through the downspouts and piping
  Remove debris and pre-clean the water
  Store the water
  Pressurize the water to the intended use
  Disinfect the water if the water is being used for potable (drinking)

A rainwater collection and storage system can be as simple as capturing rain in a barrel for gardening or complex enough to include input from an architect, engineer, rainwater specialist and filtration and water treatment specialist.

Catchment of rainwater for outdoor use is quite simple, but even for garden water, care needs to be taken to reduce the amount of debris, i.e. pollen, bird droppings and organics that find their way to the storage tank. These organics can feed summer algae blooms in the tanks that negatively affect water quality and increase system maintenance.

Where rainwater is to be used inside the home, considerably more attention to collection techniques and pre-cleaning on the way to the cistern is necessary. This often includes debris catchment devices, gravity filters and the use of a first flush diverter.

For indoor potable (drinking) water, the raw water from the storage tanks or cistern must be disinfected with methods such as chlorine or particle filtration and an ultraviolet light. Potable water systems require an increased commitment to ongoing operation and maintenance and seasonal cleaning is also required to ensure healthy, safe water.

Detailed information on the components of a RWH system is described in the Rainwater Harvesting Components section. For the latest information on all types of RWH systems see the RDN Rainwater Harvesting Guidebook.