Rainwater harvesting - green and cost effective

'It's crazy to be paying for water to be drained off, processed by the utility company and returned to you when the original water is fine to use for flushing your toilet and in your garden,' Bob Imrie tells me.

	Jules Young next to the water tap that delivers the harvested rainwater (left) and in her garden

Instead, he channels the rain that lands on the roof of his three-bedroom home through a filter and into a tank sunk under his lawn. It is then pumped to his toilet, washing machine and an outside tap, enabling him to slash his water bill by at least 40 per cent and do his bit for the environment.

It also provides him with an emergency supply in the event of a hosepipe ban.

The Freerain ( www.freerain.co.uk ) system was already in place when Mr Imrie moved into his home in 2001, but typically costs £2,000 to £5,000 to retro fit in an existing property.

And with climate change experts warning that water shortages will become increasingly common, installing a system is likely to make a property far more attractive to potential buyers. In fact, it was the reason that Mr Imrie bought the house.

'I had driven past it before and not paid much attention. I had assumed the house, which is on an estate, was a standard new build. But then I read about it in a local newspaper and discovered that the properties had been built to a very high standard and designed to reduce their environmental impact.

"I suppose the property must have been more expensive as a result, but it didn't seem to be out of line with what I would have paid elsewhere.'

As a result of the rainwater harvesting system, and other eco technologies in his Nottinghamshire home, Mr Imrie's monthly water bill is just £7.

But despite the pressing need for water conservation, the industry is in its infancy in the UK, with only around 5,000 domestic properties benefiting from the technology. This is due, in part, to the fact that just 20 per cent of homes are metered and therefore most householders lack a financial incentive to cut water usage.

But Mr Imrie also believes that the Government is failing to promote the technology. 'It's mad that the Government hasn't made rainwater harvesting the standard for new builds,' he says.

It has also failed to offer grants to homeowners wishing to install the technology, unlike in Germany, where a mixture of carrot and stick has led to more than half a million rainwater systems being installed in homes and workplaces.

However, there is an additional financial advantage from installing the system that few people are aware of. 'About 5pc of your water rates cover drainage from your house,' Mr Imrie says.

'In my case, a pipe comes from downpipes off the gutter, goes into the tank and exits to the nearby dike, so if it's over full it flows into the dike That means I can get a reduction, but the water companies won't tell you that. It's only because I've worked in consumer law for years that I was aware of this,' says the former trading standards officer.

John Thorne retro-fitted a system to his four-bedroom property in Leicestershire last year and his only regret is that he didn't fit an even larger system.

He installed a number of green technologies, including solar panels, during the refurbishment, but it is rainwater harvesting that has impressed him the most. 'It is the most reliable and trouble free of the various systems we installed.'