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by Andy Thompson, Sales and Commercial Manager for Titan Pollution Control, which manufactures Envireau rainwater recycling systems
The current drought in the South-East of England has emphasised the need for water conservation to be put at the top of the agenda for house-building.
It is likely that the current trend for short, sharp bursts of rain that cause soil erosion and flooding, and do little to fill underground aquifers, will continue. In addition to this, household water consumption is increasing.
With rainfall in such short supply, it is no longer viable to use treated drinking water for everything from flushing the toilet to watering the garden. We need to find alternatives to treated drinking water, as well as reducing the overall amount we use.
Rainwater recycling - an ancient form of technology that predates mains water supplies - provides a crucial method of conserving water and could be of great benefit to householders and businesses alike in drought stricken areas of the country.
Rainwater recycling systems were introduced to the UK only about eight years ago and are currently installed in about one per cent of new developments in the country. However, they have long been popular abroad. For example, they have been used for about 20 years in Germany, which does not have as much rainfall as the UK and is more reliant on groundwater.
Studies show that 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.
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. It can even be brought up to drinking standard, if required.
Recycled 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.
So what do rainwater recycling systems do? Basically, they 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 appliance.
It is also possible to buy systems that pump rainwater direct to an outside tap. These systems can be of great benefit to keen gardeners beset by hosepipe bans since they can store large quantities of water. They can be easily retro-fitted too, since no internal plumbing work is required.
In addition to helping to conserve water, rainwater recycling systems can also bring significant savings to people on water meters. For example, a full rainwater recycling tank for a two-storey house with a 100sq metre roof could provide enough water for 200 toilet flushes, 30 full washing machine cycles and 12 car washes. A 100 sq metre roof area can yield up to 120m³ of rainwater per year with a value of up to £2.56 m³, giving an annual saving of £256 for a property on a water meter.
Savings for businesses, which tend to consume much greater quantities of water, can also soon be realised. For example, a typical hotel in the South West of England, which is on a water meter and uses water for a variety of non-potable purposes, including toilet flushing and laundry, could save the £15,000 cost of a system in about two and a half years. These calculations are based on a roof area of 2,000m², which could collect up to 2,714,000 litres of water per annum, based on an average annual rainfall of 1357mm each year. A combined water charge per m³ of £2.26 puts the value of useable rainwater at £6,133.64 per annum.
Another benefit of rainwater recycling systems is that they can help to avert flooding. Many local authorities are now demanding that the discharge of surface water from such development sites must be no greater than if the land was being used for agricultural purposes.
Rainwater recycling systems can enable developers to meet such stringent planning requirements by reducing the surface run-off during heavy rainfall. When the rainwater has been recycled, it passes through the foul system, rather than the storm drains, meaning it poses no flood risk.
Rainwater recycling systems, such as Titan Pollution Control’s Envireau are designed to be as user-friendly as possible. Installing a system like Envireau is therefore 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.
To conclude, rainwater recycling provides a viable means of conserving water supplies and making the best use of a natural resource that we simply can no longer afford to throw down the drain. The UK market for rainwater recycling, which was last used as a mainstream source of water in the nineteenth century, has increased by around 300 per cent in the past two years. We believe that this trend is set to continue and we expect that rainwater recycling systems will become an integral part of new housing and commercial developments in the future.