Desalination for London – techno-fix or necessity?

London is predicted to have 800,000 new residents by 2016, with a rising number of single occupancy households that use proportionally more water.

At times when demand for water is at its peak – hot summer bank-holidays for example – supplies are already insufficient in parts of east London. Household demand for water continues to rise as affluence brings more water-hungry gadgets and appliances.

The £200 million desalination plant proposed by Thames Water is seen as the solution, a means to quickly close the gap between supply and demand for a minimum social and environmental cost. On those points it would be difficult to argue. Impacts on the internationally important wildlife of the Thames estuary are likely to be few, with some lingering concerns over the disposal of the highly saline waste stream and the ‘footprint’ of the desalination plant. The energy demand of the plant has seen its initial rejection, but a commitment to powering it through renewable energies could overcome climate change-related concerns.

What then is the problem with this ‘solution’ to the capital’s water security issues? The desalination plant on the Thames estuary at Beckton symbolises the failure of Thames Water and its regulators to embrace sustainability and tackle hard issues. Rising demand is seen as inevitable, something to be factored into future plans and not questioned.

Other cities across the world have been in a similar situtaion to that now faced by London. Rather than accepting the need to supply rising demand, they have instead sought to reduce it, to postpone or prevent the need for expensive and unsustainable new supplies. New York, for example, has embarked on a huge programme of water efficiency – replacing hundreds of thousands of water hungry toilet cisterns, installing water meters and adopting a demanding water use standard. As a result of these actions, water consumption per person declined from over 200 gallons in 1991 to 136 in 2004, and proposals for new reservoirs and treatment works were dropped.

In support of their desalination plant, Thames Water claim to be working hard to encourage their customers to use water more efficiently, but say that “water efficiency will not be enough on its own to take away the need for the desalination plant.”

Unfortunately the facts tell rather a different story. Between 2002 and 2005, Thames spent on average just £420,223 a year on water efficiency measures – not including investment tackling leakage – which amounts to about 5p per person (Every Drop Counts: Achieving greater water efficiency, Ippr 2006). Not surprisingly these efforts saved a mere 0.3688 million litres per day, a tiny fraction of the 862 million litres per day Thames Water lost in leakage in 2005/06.

Given the size of these ‘savings’ it is not surprising that Thames appears to have little faith in suppressing demand, and have instead sought their expensive ‘techno-fix’. However, it must be clear that the current activity by Thames is by no means a comprehensive programme of water efficiency. Meeting rising demand rather than tackling waste and non-essential use is not a strategy compatible with sustainability, nor with our efforts to tackle climate change.

The process of abstracting (or desalinating), transporting, and treating water uses energy. On average, 1 million litres of water requires 468kWh to supply, producing 209kg of CO2, while 1 million litres of wastewater requires 437kWh to treat, producing 195kg of CO2 (BRE, 2004).

Instead of prematurely admitting defeat on water efficiency, Thames needs to get serious about saving water and take real steps to reducing demand. For example, the British Bathroom Manufacturers Association believe there are over 10 million toilets that still use 9 litres or more to flush, when modern low flush models can do the job with just 4. A programme of putting water efficient toilets, taps and showers into Londoner’s homes, alongside fitting water meters, would in a few years narrow the gap between supply and demand and save customers money too. Judging from the water resource plans of Thames Water, such a large-scale programme has never been considered.

Rising demand from population increase and new household formation cannot be prevented by water company action alone, but can be addressed through building codes and regulations, and through local authority policies and design briefs. New homes built under the higher levels of the new Code for Sustainable Homes could, for example, use 40% less water than current standard new homes.

Given the supply-demand gap in eastern London it is vital that such standards are adopted there. There is also much interest in the concept of ‘water neutrality’, where any increase in water use from new housing is offset by reductions elsewhere – whether through retrofitting water efficiency measures into existing properties or through tackling leakage.

Building a desalination plant on the Thames is the easy way of meeting the rising gap between available supply and demand in London. It’s an easily achievable ‘quick-win’ technological fix. But in avoiding the real problem of rising water use it fails the crucial test of sustainability and necessity. London and Thames Water should embrace the lessons from other great cities of the world, and tackle water wastage now, to avoid costly, environmentally unsound and unnecessary investment.

Phil Burston

Senior Water Policy Officer

Royal Society for the Protection of Birds