A rainwater tank is used to collect and store rain water runoff, usually from rooftops and gutters. Rainwater tanks are installed to make use of rain water for later use, reduce mains water use for economic or environmental reasons, and aid self-sufficiency.
Any rain that falls on the uphill side of the Griffith University EcoCentre roof is collected in a split-level, two-tank water storage facility holding 20,000L situated under the building. This tank water is used for toilet flushing and non-potable water use in the hand basins. The tank system switches automatically back to mains water supply in times of low rainfall. This system represents a potential saving of 357,000 litres of water per year.
A wet composting system takes sewerage and greywater from the toilets, hand basins and shower and passes it into a digester tank. Here worms and microorganisms break it down to form a solid material that can ultimately be used for soil enrichment. The digester is also capable of receiving compost materials such as food scraps, paper and cardboard. Liquid waste from the digester is pumped to an activated sand filter bed. This renders the effluent fit for pumping to under-soil irrigation pipes to restore water flow to the forest.