Water Neutrality: Easing the Pressure on Supply
The sustainability debate seems to have been almost entirely dominated by energy and the "zero-carbon" future. This pursuit, however, has tended to obscure water efficiency as an equally important key to unlocking sustainability. Dr Gareth Evans investigates what it means to become water neutral.
When companies such as Coca-Cola, Pepsi and Cadburys start making pledges to become "water neutral" within years, headlines are guaranteed, and not without good reason. The idea of embedded energy – the total amount of energy required to make any given product, get it to its point of use and then dispose of it at the end of its useful lifetime – has become a familiar one; but by contrast, embedded water is something all together more novel and newsworthy.
Calculating these composite water costs reveals some surprising results. According to the "State of Green Business 2009" report from the aptly named Green Biz organisation, "a cup of coffee, for instance, has 140l of embedded water, when you consider the amount used to grow, produce, package, and ship the beans. A hamburger contains 2,400l."
Water is the new carbon
Although there is an obvious case for food and beverage firms to address their water usage, as industry consultant Bevan Rees explains, the real impact of this nascent paradigm of water neutrality is likely to be felt elsewhere.
"Sustainability's all about balance. If we're going to build more houses – and all the demographic forecasts and population predictions suggest we're going to have to – then it's pretty obvious that you've got to balance the demand, especially when water resources are under pressure already," says Rees.
New developments can't be allowed to simply add to that burden and that's where being water neutral comes in. Water's going to be the new carbon – but it'll call for a period of adjustment."
Rees points to the situation in the UK, where despite the adoption of the Code for Sustainable Homes in April 2007, water efficiency – one of the cornerstones of the policy – remains almost forgotten amid the grandstanding of its energy-related aspects.
From the perspective of enhanced sustainability, there is evidently much to be gained by a step change in emphasis; the Environment Agency (EA) defines neutrality as when "the total water use after a development does not exceed the total water use before development." It is an undeniably ambitious target, but the thinking behind it is beginning to take root.
Scope and strategies
The obvious place to start is with the public water supply, which accounts for just under half of all abstractions licensed by the EA, and the nature of the housing stock being developed. With the precept of water efficiency integral to the new code, there is a clearly mandated requirement to address usage issues and the need for built-in measures for houses and buildings to comply. Making better use of the water actually supplied to households will undoubtedly represent a major contribution towards neutrality, but even with the bulk of the necessary savings being met in this way, as is intended, it is probably unrealistic to expect that this alone will achieve the goal.
A range of supporting strategies have been suggested to make up the difference, including the likes of rainwater harvesting, enhanced leakage avoidance, storm overflow provision and even the potential involvement of wastewater discharge, depending on local circumstance.
Such moves to lessen the immediate effect on local water resources, reduce losses and improve the management of river flow clearly have much merit, but they also raise some fundamental questions about the nature of neutrality and the knock-on effects it might have.
"There's only so much rain that falls – even in a fairly wet place like the UK," says Rees, "so while rainwater harvesting sounds like a great idea, if everybody does it, there's bound to be consequences for the rest of the catchment. Then there's all the talk about grey water recycling. It's another great idea – but only if it's done right; get it wrong and you risk concentrating pollutants in the wastewater or boosting potentially harmful bacteria in the soil. To make enough of a difference, it needs to go a long way beyond simply pouring your old bathwater into a bucket."
Making it work
Without doubt, the measures being suggested can make a huge difference in terms of reducing an individual property's dependence on mains water and easing the pressure on supply caused by a development as a whole, but they must be done effectively and they must be additional. Existing strategies for leak fixing or catchment management, for instance, cannot be viewed in the context of measures for neutrality; a new development intrinsically calls for novel planning.
There is no off-the-shelf, one-size-fits-all solution and the concept of water neutrality is probably best seen as a tool to advance the cause of water efficiency and sustainable use, rather than as a hard and inflexible rule. Even the EA concedes that there may well be some cases for which a target of less-than-complete 100% neutrality would be more appropriate.
Part of the problem is that it is still early days for the whole idea and working out how the over-arching goals can best be translated into practical realities on the ground largely remains a work in progress.
Even assessing the level of supply and demand uncertainty – a routine enough task in the industry – becomes more complicated when the headroom safety margin required for full neutrality depends on additional factors and a raft of novel measures.
In the end, however, it is not a challenge that the industry alone must face. There are many stakeholders – policy-makers, regulators, household consumers, environmental groups – who will all need to play their individual parts. As Pamela Taylor, Water UK chief executive said at the 2010 Institute of Water annual conference, "everyone agrees that sustainability can't be based on the demands of one set of interests – whether consumers, or the environment, or the economy. It has to be a joint project."
For water neutrality to work as envisaged, the strength of that consensus will doubtless prove critical.