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This week we ask: Should water companies adopt sustainable urban drainage systems (SUDS)?

Water companies stand accused of flouting government guidance by refusing to implement urban drainage strategies that reduce flood risk.

Yes

Pierre Williams, Housebuilders Federation Developers favour

SUDS because they offer environmentally friendly methods of water management. SUDS may also be less expensive to repair and maintain.

Advantages also include the potential to create bio-diverse public open space such as ponds and wetlands, provision of an attractive water frontage for some properties, and the fact that they allow development to take place in areas with nearcapacity (or overstretched) sewerage infrastructure.

The major impediment to the take up of SUDS is the reluctance of stakeholders such as water companies and highways authorities to abandon their preference for traditional systems. They are generally unwilling to adopt SUDS in lieu of normal piped sewerage systems.

This may be down to an ultracautious approach to innovation, a feeling that their shareholders' interests are best served by the construction of network 'assets' using known technologies; and/or directions from their own legal departments.

When water companies and others do adopt SUDS, they can upset cost calculations by demanding punitive, over-cautious lump sum payments from developers to set aside for future maintenance purposes.

However, housebuilders feel that, if other stakeholders were to play their part, SUDS could become the 'norm' for new developments (in areas where soil contamination is not an issue).

The Environment Agency is not supportive of the concept of 'private' management of drainage schemes, because of the concerns about long term viability of such arrangements.

Essentially, this is in line with HBF's view that developers, owners (including private management companies) should not be left with this sort of liability and that agencies such as sewerage undertakers, highways authorities and like bodies must ultimately be the custodians of such systems.

No

Mike Waddington, policy planning and membership, Water UK

Water companies have a legal duty to 'effectually drain' an area. The key words here are 'legal duty' and 'effectually'.

What is effectual? That depends on the hydrogeology of an area, the system being installed to the correct standard and understanding the interaction of the SUDS with the piped systems.

Water companies do pragmatically adopt SUDS systems that are appropriate to local conditions. But they shouldn't be expected to adopt all SUDS systems in housing areas in advance of proper design standards.

There has been too much generality in this debate - follow the business cliché: think global but act local; it is not a question of SUDS in general, but of SUDS (and the techniques are numerous) in Birmingham, Chichester, Aberdeen or wherever.

There are also legal difficulties: the law says SUDS are not sewers, and therefore not adoptable so the regulators will not fund them. Local and highway authorities are also key players and must themselves take responsibility. However, we want to sort this out.

We are part of a £700,000 three year research project, being conducted for our water industry research arm UKWIR by Binnie, Black & Veatch, to gauge how SUDS perform in terms of hydraulics and water quality, and determine real costs.

Crucially, we are also working with government, the Environment Agency, Ofwat, local authorities and others to come up with something like Sewers for Adoption for SUDS systems.

We must avoid a proliferation of private maintenance arrangements that can - no will - break down and bequeath the next generation with a new 'private sewers' headache.

We need to convince people and the insurance industry that SUDS are not a leap of faith but a truly tested, sustainable solution.

The facts

lSUDS are made up of one or more structures built to manage surface water runoff. They are used in conjunction with good site management to prevent flooding and pollution. The main methods of control include:

prevention, that includes minimising run-off in the first place by avoiding construction of large paved areas; using filter strips and swales that are vegetated surface features that drain water evenly off impermeable areas; permeable surfaces and filter drains, such as grass, gravels and porous pavements that provide some storage; infiltration devices such as soakaways; basins and ponds for water storage and attentuation.

lConstruction research body CIRIA is running an event this autumn called In the know about H 20 - Implementing sustainable water management in the built environment.

The day will include presentations on the barriers to implementing sustainable water management and will include examples of good practice where the barriers have been overcome. Further details can be found on www. ciria. org. uk/suds

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