All rainwater recycling systems operate using typical roof drainage layouts. This means rainwater runs down the roof and into the guttering and fall pipes in the normal way before passing through a filter, which removes the leaves and grit. The rainwater is then stored in an underground tank containing a pump and filter.

The Gravity system pumps water to a dedicated header tank in the loft space via an inline filter, which further cleanses the water. One of the great advantages of this system is that the header tank also has a mains water supply, so if the pump was unable to work due to a power cut, or the underground tank became empty, the system would automatically switch to mains water. The above systems are not usually retro-fitted to existing properties because of the extensive internal plumbing work required.

In addition to helping to preserve a valuable resource, rainwater recycling systems also make particularly good sense economically for people building new homes, since all new domestic and commercial properties in the UK are automatically connected to water meters. A full rainwater recycling tank for a two-storey house with a 100m² roof could provide enough water for 200 toilet flushes, 30 full washing machine cycles and 12 car washes. A 100m² roof area can yield up to 120m³ of rainwater per year with a value of up to £2.56m³, giving an annual saving of £256 for a property on a water meter.

Another key advantage is that when the rainwater has been used, it passes through the foul system, rather than the storm drains, meaning that it poses no flood risk. Consequently, rainwater recycling systems are becoming a necessity for gaining planning permission in some areas of the UK that could be at risk of flooding, particularly where regulators insist that surface run-off must be no greater than if the land was used for agricultural purposes.