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Last Updated: Wednesday, 25 July 2007, 16:37 GMT 17:37 UK
Sewerage systems of the future?
By Sarah Mukherjee
BBC environment correspondent

Could reeds be the new pipes?

Few people realise when they eat their lunch by the lake and fountain at the M40 service station to the south of Oxford, that they are looking at some cutting edge drain technology.

The deep green reeds, yellow water lilies and gently splashing water simply look like an attractive water feature.

But in fact, this Sustainable Urban Drainage System (Suds) could be the future of sewerage management.

"This is using technology and engineering to slow the water down from when it comes from the sky to when it gets into the river" says Simon Hughes, flood risk assessor from the Environment Agency.

"It uses the lakes to make sure that heavy rain doesn't run into the system too quickly".

The first drains built in Britain were Roman, and since then, engineers through the ages have tried to find the most effective way of removing waste from increasingly urban areas.

We have to find other ways of managing rainwater
Simon Hughes, Environment Agency

This has left water companies with a patchwork of old and ineffective pipes - in some cases, museum pieces - still taking the water.

The cost of replacing these with pipes fit for the 21st Century - that could deal with the warmer, wetter winters predicted by meteorologists - would run into tens of billions of pounds. And it is unlikely to happen.

"You simply cannot dig up places like Gloucester and London to place modern sewage pipes - it would be far too expensive," says Mr Hughes.

"We have to find other ways of managing rainwater."

And those ways do exist.

Rainwater collection is being put into some housing estates at present.

Instead of going into the sewers, the water is collected, filtered and stored in tanks buried in the garden. It can then be used for flushing the loo or for washing - reducing water use by up to 50% and also helping to manage the water cycle.

Building experts say these sustainable methods of managing water could be made compulsory within two years.

One said: "Builders would moan about it, but it could easily be done".

Private drains

But the government's recently published Code for Sustainable Homes, which includes water efficiency measures for those houses that will get the top ratings, will not be fully in place until 2016.

There are those in the environmental movement who feel the government has not been bold enough in bringing forward this code.

And there is a more immediate issue with the country's sewerage system.

About half of the sewers connected to domestic property - perhaps 100,000 miles (161,000 km) of pipe - are privately owned.

Householders are often unaware of their responsibilities to maintain these drains, and water companies don't even know where they are.

The government has agreed that these private drains should be handed over to the water industry to maintain - but there has been no decision yet on how to implement such a plan.

Graphic showing some of the factors that contribute to flooding problems
1 Most old drains combine foul and surface water, which in heavy rain overflows into rivers
2 Interceptor sewers can collect this overflow and divert to treatment works before it reaches rivers
3 Sustainable Urban Drainage Systems mimic natural drainage, slowing water flow and reducing the amount running off into drains
4 Disposing of unsuitable material into sewers via toilets and sinks can cause waste to back up and overflow
5 Fat traps can intercept some of the offending material from commercial premises
6 Reducing water consumption not only helps the environment but reduces load on the sewerage system
7 Paving over gardens prevents water draining into the ground, adding to pressure on the system caused by rain "run-off"


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