Rainwater Harvesting is the collection of rain water that would otherwise have been lost and has the potential to save large amounts of mains water and, therefore, reduce the pressure on this increasingly valuable resource. Large surfaces such as roofs or driveways are ideal and can provide up to 100m³ (100,000 litres) of water per year from a medium sized area. This water can be used to flush toilets, water gardens, and even in certain circumstances to feed white goods that don't require drinking level water, such as washing machines.