Digging for rain

Harvesting water from the sky can stop environmental damage, prevent floods and save cash. Will Anderson explains how it's done
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The Independent Online

What's the definition of a self-builder? Someone who puts brick on brick in all weathers, huddling in a caravan at night in the sure knowledge that the house will never be ready for Christmas? Or someone who dreams up a fantasy home, but leaves the hard work to a contractor, only visiting the site to get in the way and give the foreman something to complain about?

What's the definition of a self-builder? Someone who puts brick on brick in all weathers, huddling in a caravan at night in the sure knowledge that the house will never be ready for Christmas? Or someone who dreams up a fantasy home, but leaves the hard work to a contractor, only visiting the site to get in the way and give the foreman something to complain about?

I confess that I am closer to the second description than the first, though our site foreman, Steve Archbutt, is unfailingly cheerful. This week, however, I finally got my hands dirty. Paying my morning visit to the site, I found Steve and four other men sinking into the mud, as they struggled to shift the concrete sleeves for our underground rainwater tank. I couldn't just stand there and watch their pain, so I was rapidly - and literally - roped in.

Life on a building site in London is a truly multicultural experience. Did you hear the one about the Englishman, Scotsman, Russian and Albanian trying to build a concrete water tank without a crane? The Englishman gave the orders, the Albanian complained bitterly, the Russian ignored them both, and the Scotsman (that's me) did his liberal best to respect all their opinions in order not to lose any fingers. Five hours and a lot of pan-European swearing later, the tank stood solidly in its hole and Steve assured me that nothing in the entire build would be as tough.

Rainwater collection, or "harvesting" as it is romantically called, makes good ecological sense for two reasons. First, it eases the pressure on the mains water supply, reducing upstream energy and environmental costs - last year English Nature reported that 160 wetland nature reserves were in danger of drying up because of ground-water extraction. Secondly, it reduces the risk of flooding during storms by buffering the deluge before it hits the drains. This is an increasingly important function: images of English villages under water are becoming familiar, and earlier this year thousands of fish died when London's sewers were overwhelmed, flushing raw sewage into the Thames. You can also slow down the rain by planting a garden on your roof, using water-permeable paving or building soakaways.

Rainwater is a great resource, but the more of it you want to use, the more kit you need. To provide for your garden, all you need is a tank or water butt. To use water inside your home, you will need a much bigger tank, a completely separate set of pipes from those carrying mains water, plus an electric pump and some filters. To do anything beyond flushing toilets, and possibly clothes washing, you will need chemical or biological filtration as well.

So what's the most ecological choice? The answer is not obvious, as the more complex the kit, the greater the ecological costs of the system - pump energy, maintenance and capital depreciation all have hidden burdens. If you are ultra-efficient in your use of water, the savings of full-scale rainwater harvesting may be meagre. The sums look much better for larger developments and for commercial settings (where most of the water goes down the toilet and bubble baths are rare).

The more complex approaches also require maintenance - and therefore commitment. If you don't clear your gutter regularly, your toilet will begin to smell of rotting vegetation. This is a significant issue, for if ecological design is to become universal, it must be robust: it must work for everyone, not just the committed.

Our rainwater tank will replenish our pond, water our garden and keep us going in emergencies. Rather than pumping rainwater into our home, we are using good design inside to minimise our water consumption. Our two toilets will be state of the art (see below) and our appliances will be ultra-efficient in both energy and water use. Our taps will be fitted with aerators, which give you a fuller flow for less water, and flow regulators, which prevent high-pressure systems losing gallons of water whenever you turn a tap on. The brand we have specified, Hansgrohe (www.hansgrohe.co.uk), incorporates both of these technologies in its bathroom taps as standard. In Germany, everyone's water is metered and prices are much higher, so it's not surprising that it's a German company leading the way here (happily German design looks great too).

In the festive spirit, here's a quick quiz to round off my building year:

1. What's the most water-stressed city in Europe?

a) London. b) Madrid. c) Istanbul.

2. How much of our drinking-quality tap water is actually used for drinking or cooking?

a) Less than 1%. b) 5%. c) 20%.

3. Will we be showering in Tree House by Christmas 2005?

a) Without the slightest doubt. b) You can tell he's a rookie. c) Dream on.

The answer, of course, is "a" in every case.

For more on rainwater harvesting and details of suppliers, see the UK Rainwater Harvesting Association website: www.ukrha.org.

SUPER LOOS

The Ifö Cera ES4 lavatory, available from the Green Building Store, is the epitome of robust ecological design. It is the most water-efficient lavatory on the market, yet it doesn't even have a dual flush.

Dual-flush lavatories make sense, but they have their problems: choose the wrong button and you may have to flush again. And because the flush mechanism uses valves rather than the usual siphon, the lavatory is more likely to jam or leak in the long term.

The ES4 is a single-flush siphonic model that never leaks, and it uses only 4.5 litres per flush. It can neither be misused nor go wrong without your noticing. And it isn't even German. Although the make is Swedish, it was designed by the UK company Elemental Solutions. Its website (www. elementalsolutions.co.uk) is a great source of information on water efficiency and natural sewage systems.

For the Green Building Store, call 01484 854898 or see www.greenbuildingstore.co.uk.

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