A Water Grid for the UK? CIWEM’s position on the matter

A nationwide water transfer grid is a technically feasible solution to dealing with imbalances in water resources supply and demand across the country; but it would be a relatively expensive option, and it is not yet, or for the foreseeable future, a necessary option, in CIWEM’s view.

Problems with a nationwide grid are:

• the financial cost
• the environmental cost
• social equity – it would be a grid to get water to southern England from (and not to) northern England, Wales, Scotland and Northern Ireland

A recent review by the Environment Agency (Do we need large-scale water transfers for south east England?, September 2006) estimated that the capital construction cost for the reservoirs and pipelines needed to store and transfer water from northern England to southern England would be around £8-14 million per megalitre of water per day.  To transfer water from Wales, costs would bearound £2.4 million per megalitre per day, plus around £3-5 million per megalitre per day of environmental costs if transfers of water from the River Severn were involved.  Alternatively the construction cost of building new reservoirs in southern England would be around £1.6 million per megalitre per day (though there is then the question as to whether the reservoirs could be filled by rainfall and non-adverse abstraction). 

Other options that are economically and environmentally more attractive than a national water grid are to:

• manage the demand for water (in times of shortage, and more generally)
• reduce the wastage of water (in leaks, in unnecessary use and in inefficient use)
• meter homes in areas at risk of shortage, to encourage and incentivise the prudent use of water, and to enable charges to be varied according to the volume taken, or to the availability of resources
• recycle and reuse water (many indirect reuse schemes already exist – of both planned and unplanned type)
• transfer water locally, between adjacent regions, using rivers, canals and pipelines (many small scale water transfer schemes already exist)
• store more water in reservoirs, capturing it when it is available, and releasing it when it is not
• store more water in aquifers, recharging them (artificially) when it when it is available, and releasing it when it is not
• use surface and groundwater resources more conjunctively, resting groundwater sources when surface water supplies are plentiful, and reserving groundwater sources for supply and environmental gain in times of shortage (this is done now, but there is scope for more).

Large scale transfers of water could lead to the deterioration of providing (donor), carrying (transfer) and receiving water bodies (from over-abstraction, acidification, ecological damage, transfer of fish parasites or alien species), contrary to the provisions of the European Water Framework Directive.  When less costly and less environmentally damaging options are available, the strategic transfer of water would not be considered an acceptable reason under the legislation for allowing a water body to deteriorate.

A sustainability appraisal of large-scale and/or high volume water transfers would undoubtedly reveal the following impacts:

1. The large scale transfer of water would require substantial pumping of raw water, and hence electricity usage and carbon emissions would be high relative to more local options.  The problem would be exacerbated by any need to pump water up and over hills – as would be the case in transferring water from the Severn to the Thames, for example.

2. The large-scale transfer of water is based upon moving water from geographically remote areas, and hence it is not associated with optimising local resource management or re-use.

3. If a nationwide transfer system was used only occasionally, to meet  human and environmental needs in periods of prolonged drought, the cost of meeting those needs would be extremely high, per volume of water transferred.

Colin Fenn
For the CIWEM Water Resources Panel, May 2007