Rainwater harvesting saves up to 50% of mains water consumption in a home and varying amounts in commercial properties, schools and hospitals. In April 2010 new building regs will come into force which will for the first time make water consumption limits obligatory for all new construction. Rainwater harvesting is the way to meet these targets.
The more eco-conscious home owners or operators have realised that the powerful 230 Volt mains electric pump required to move the rainwater from the underground storage tank round the building uses quite a lot of mains electricity, which increases the carbon footprint of the installation. This concern over pump energy consumption, plus lack of water during power cuts, pump noise, and unsightly or bulky control panels led to the creation in 2008 of the Rain Director® with its smart header tank. Instead of the pump in the underground tank feeding the appliances directly, it pumps into a smart header tank which in turn feeds appliances by gravity. The pump only runs when the header tank is completely empty rather than every time, for example, a WC is flushed. This already reduces pump energy use by a factor of 5 (calculations available).
The Solar Rain Director® further reduces this power use. A small solar panel (the size of small car windscreen), a submersible 12 volt pump and a battery ensure rainwater can be pumped to the header tank without any use of mains electricity. Both the control panel and the pump are powered by the battery which is kept topped up in daytime by solar power. Tests show that even on a cloudy day, the latest solar panels can deliver six times the charge needed to run a typical family house. In the unlikely event of the panel not providing enough charge to the battery, mains electricity is used as backup. In a further innovation, unlike normal chargers, the standby mode of the mains charger takes no current at all, not even a trickle.
So the powerful mains-electric pump is replaced by a small 12 volt pump which pumps to 8-10 metres high, enough to feed the Rain Director’s smart tank on a two story house, and one or more relay pumps, with supplemental solar panels, can be used in taller buildings. The Solar Rain Director does not provide enough pressure for outdoor water use except where gravity feed is sufficient.