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Andy Thompson, Sales and Commercial Manager for Titan Pollution Control, which manufactures Envireau rainwater recycling systems, answers your questions
Q. Is it worth recycling rainwater?
A. Yes, studies show 55 per cent of domestic treated water could be substituted for rainwater; while 85 per cent of water used for commerce and industry does not need to be of drinking standard.
With treated water in such short supply, it makes sense to look to other sources for many of our everyday needs. Rainwater can be safely used for a variety of non-potable purposes in and around the home, including flushing toilets, running washing machines, cleaning cars and watering the garden.
Rainwater can also be invaluable for industry – one of the largest water consumers –where it can be used for factory cooling systems, and cleaning vehicles and equipment, for instance.
Q. How do rainwater recycling systems work?
A. These systems allow rainwater to be collected, stored and re-used, and eventually discharged through the foul system. All rainwater recycling systems operate using typical roof drainage layouts. 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 water is then stored in an underground tank containing a pump and filter.
Some systems pump water to a dedicated header tank in the loft space via an inline filter which further cleanses the water. Others pump rainwater direct from the underground tank to the appropriate household appliance.
It is also possible to buy systems that pump rainwater direct to an outside tap. These can easily be retro-fitted, since no internal plumbing work is required.
Q. Is it true that you can make substantial savings by recycling rainwater?
A. Yes, the pay back for businesses and homeowners that invest in rainwater recycling systems can soon be realised. A car dealership in the south of England, which needs water for a variety of non-potable uses, particularly car washing, could get pay back on the capital purchase of a £3,500 rainwater harvester in about a year if it was on a water meter. These calculations are based on a roof area of 3,129m² and an average annual rainfall of 942mm, which means the tank could collect 2,947,518 litres per annum. If the combined water charge per m³ was £1.19, the annual value of useable rainwater would be £3,507.54.
Q. Do rainwater recycling systems have any other advantages?
A. 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. The systems control surface run-off by capturing and storing rainwater. The rainwater then passes through the foul system, rather than the storm drains, meaning that it poses no flood risk.
Q. How do you install a rainwater recycling system?
A. Installing a system like Envireau is a simple process utilising the trade skills of a plumber, electrician and civil engineering contractors.
The civil engineering contractor is responsible for the excavation of the storage tank hole, and for connecting the drainage, ducting and supply pipe to the tank when in place, and backfilling with concrete. The leaf filter installation and location are also their responsibility.
The plumber carries out the internal connections to the supply pipe and control unit.
Electrical installation consists of wiring a mains supply (240v) into the control unit via a dedicated RCD, and wiring in the six-core signal cable for the depth sensor.
Q. How popular is rainwater recycling in the UK?
A. Rainwater recycling systems are currently used in about one per cent of new developments in the UK. However, this figure is expected to rise due to water shortages and new building regulations designed to control surface run-off and prevent flooding.