Overlooking the obvious

Rainwater harvesting can drastically cut water demand - yet it is being grossly underestimated, writes Chris Williams.

Picture the scene – a summer view of Weir Wood Reservoir near East Grinstead in the South-east. The parched and cracked landscape looks more like something from a foreign land than a key source of water for the people of East Sussex.

It is a picture that speaks a thousand words: drought restrictions still prevail in many parts of the UK, and the media remains full of warnings of climate change. It may seem melodramatic to speak in terms of the UK’s water crisis – but the challenges for sustainable demand management are undoubtedly real and pressing.

Water efficiency is a regular mantra among all stakeholders with a part to play in managing the ever-increasing demands made on the UK’s water supplies. The Environment Agency (EA) advocates active promotion of water efficiency, and the water supply companies have a statutory obligation to promote water efficiency.

But there is at least one technology which has huge potential to reduce water demand which at present is being grossly underestimated: rainwater harvesting.

Collecting and recycling rainwater using a simple, low-maintenance technology is not a new idea. It is already a well established practice in other countries with similar demand management challenges to the UK, particularly Germany, the US and Australia.

Rainwater can be captured from the roofs of both commercial properties and homes. But the potential for using the technology in homes represents about 80% of the total opportunity.

An independent survey, commissioned by the Save the Rain campaign in association with British Water and sponsored by Hydro International, shows a high level of public consciousness for water efficiency measures. About two-thirds of people said they never leave the tap running when brushing their teeth. Fifty-five per cent recycle left-over water – watering plants. And 52% keep a jug of water in their fridge, rather than wait for a tap to run cold.

In terms of measures taken at home to help the environment, British homeowners rated saving water second in importance to recycling paper and glass, but more important than improving insulation or switching off lights. People in London and the South-east ranked top of the league of the water conscious, where the highest number of people cited water-saving as the most important environmental measure they could take at home.

Most significantly, the survey dispelled any doubts about the public’s attitude to rainwater harvesting that have been expressed by some stakeholders in the water industry. Nine out of ten believed that rainwater harvesting would be a good thing and nearly a third would be more likely to buy a house if it had a rainwater harvesting system already installed.

The popularity of rainwater harvesting is borne out by industry statistics. The market is growing at around 100% a year at the moment, with predictions for this year of 2,000 units or more. It is a rapidly increasing market.

Water demand is currently running at about 18,000-20,000Ml per day, with EA projections showing around 30,000Ml per day by 2025 unless curtailed by demand reductions and efficiency achievements.

More than 50% of this is attributable to public supply. A 10% reduction in public water demand could save 1,000Ml/d, or 400 Olympic swimming pools.

Demand management

With a sufficient critical mass of systems installed in the UK, it is easy to see how rainwater harvesting could play an important role in reducing demand.

To begin with, two million new homes are estimated to be needed by 2015 – these are mostly concentrated in the South-east and present both a threat and a challenge to water demand management.

Save the Rain wants to see rainwater harvesting made compulsory within three years on all new house building. Making systems an integral part of each new development would require specific changes to the Building Regulations.

While the public are receptive to rainwater harvesting, the Save the Rain survey indicated strongly that regulation and financial incentives would be necessary to encourage mainstream take-up. Some 63% of respondents said they would be more likely to install a rainwater harvesting system if grants were available or if they could save money on their water bills.

They said they would be less likely to install a system simply because of a wish to help the environment or because of worsening drought conditions in the UK.

Grants are already available to install rainwater harvesting in industrial properties, through the Enhanced Capital Allowance scheme.

While paybacks on commercial properties can be three to five years, for domestic properties the period is more likely ten to 15 years. It should be possible to introduce a system of fiscal incentives for private dwellings, perhaps based on grants systems offered for insulation in private properties, or through other forms of subsidies.

Other countries’ experiences that have exploited rainwater harvesting as part of water efficiency measures provide useful examples. In Japan, rainwater harvesting systems are compulsory on developments above a certain surface area.

A variety of regulatory measures and incentives are offered in the US, ranging from making rainwater harvesting compulsory on new-build (for example in New Mexico) providing significant rebates on installation costs (for example in San Antonio).

In Atlanta, Georgia, rebates of up to £21,000 are available. Elsewhere in the US, there are tax exemptions on rainwater harvesting equipment.

In Germany, government subsidies of up to £1,000 are available, while in south Australia all new house builds must have rainwater harvesting, and grants are available.

Clearly if rainwater harvesting is to achieve its role in water demand management, then certain barriers will need to be addressed. Most importantly, it will require a review of water company charge structures.

For the consumer, where water is metered, rainwater harvesting can deliver savings of up to 50% on water bills. But the water companies still have to make water available and still have to deal with the same amount of effluent treatment.

Again international experience may help to point the way and revising tariffs could be a solution to helping water companies meet water efficiency targets without taking a huge hit on their revenue streams.

Rainwater harvesting as a proven technology presents a real opportunity. It is one that can assist greatly in resource development and demand management if adopted on a widespread scale in the UK.

To lobby for change within the UK regulatory regime, Hydro International is sponsoring the Save the Rain campaign – a campaign to promote water efficiency and financial incentives to gain wider use of this effective technology.

Chris Williams is managing director (Europe) at Hydro International. Call the Save the Rain campaign on 0800 294 0105.

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