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Recycling and harvesting water

By garden designer Alice Bowe. Hints and tips for creating more eco-friendly and sustainable garden designs.

Rainfall is becoming less predictable in our changing climate and so an important part of sustainable garden design planning relates to the management of rainwater.

Hosepipe bans are now common in the UK and can last for over six months in times of drought - whilst flash floods continue to terrorise the nation.

When it rains, water from most urban buildings and hard surfaces is directed through downpipes, drains and gullies into the drainage system. Some downpipes from the roofs of domestic properties are directed into a soak-away and so return to the water table naturally but in urban areas, or from large buildings the water is whisked away into drainage systems.

This water management system not only makes our bills more expensive (with constant repairs and new drainage systems needing to be built to cope with peak rainfall) but groundwater levels drop as the water doesn't return to the water table and so we suffer from water shortages.

The average house roof in the UK sheds some 45,000 litres of water per year which means that nearly 25% of the water we currently use could be harvested from our roofs.

Rainwater harvesting

The simplest way to capture rainwater is to use diverters on your downpipes and feed this into water butts or rain barrels. Water butts are perfect for small gardens. You can buy manufactured systems or use reclaimed oak distilling barrels.

The downside of water butts is there limited capacity. Even to harvest 5% of the runoff of water from a room you would need an average of 18 water rain barrels! It can be frustrating and time consuming to effectively use water when your water butts are scattered around the garden and when used on a large scale water butts can look unsightly.

Grey water recycling

A better, but more expensive solution, is the storage of grey water and rainwater in an underground tank. This is a far more practical solution as the water can be pumped directly from the tank and used to flush toilets, feed the washing machine and irrigate the garden. Surprisingly, only 5% of the water we use needs to be drinking water so it really is a useful solution.

There is no real financial incentive to implement grey water recycling systems at the moment. A part of the problem may be that this technology is quite new and so manufacturers tend to over specify in order to cover themselves - which pushes up costs. However, as the current water supply system becomes more unreliable with the changing climate, water harvesting will become more of a necessity and less of a luxury.

With careful planning, gardens can be designed to include sustainable solutions for managing rainwater and drought. Act now!

By Alice Bowe

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