The west of England faces a possible 277 megalitre (Ml) daily water deficit by 2050 if action is not taken.
The West Country Water Resource Group has called for significant demand reduction to head off this scenario, along with effluent reuse and using existing reservoir and groundwater storage more efficiently.
At present 1,400Ml are used each day, 85% of this is domestic consumption by the population of 4.7 million people and 15% by non-household consumers.
The WCWRG, made up of South West, Wessex and Bristol water companies, has produced an emerging regional plan, modelled around five future scenarios with varying resources available and levels of demand.
These are policy future, high demand future, bad future, stretching future and alternative future.
From a 2020 baseline with 33Ml daily available in the region, the plan predicts future demand scenarios could range between a deficit of 42Ml a day to a deficit of 277Ml a day by 2050. Significant contributing factors are climate change and environmental needs to reduce abstraction. Demand reduction approaches including leakage could contribute 166Ml a day towards covering the deficit.
The south east and east of England have longer been classified as severely water-stressed than in the west, the south east is facing a deficit of up to 660Ml/day to accommodate the most extreme population growth predictions. In the east of England demand could double by 2050, with a consumption deficit of up to 2,267Ml/day predicted.
To meet future water needs the WCWRG said it does not believe moving water outside the region would be possible due to increasing water stress.
To manage demand, reductions in consumption to 110Ml/d are needed by 2050 and in line with sector-wide commitment, leakage needs to fall by 50% and efficiency measures must be implemented in the non-domestic sector. Per capita consumption for non-metered properties was an average of 194l in 2020, with household consumption higher in the South West area than Wessex or Bristol.
Strategic supply side options being investigated to enhance supplies include reservoirs, adding pumped storage to existing reservoirs and effluent recycling.
These measures will be added over three phases: 2020-30 the foundation phase in which work will begin on all outcomes. This will include a reservoir pumped storage scheme coming online in Devon and work beginning to reduce abstraction pressures via a catchment plan. During this period, water sources will be used “more effectively” and leakage and demand reduction will be underway.
Using sources more effectively could involve maximising the potential of reservoir and groundwater storage, which the West Country has substantial amounts of. This, the group said, could be used differently to make the most of wetter winters, which would have low cost or carbon impacts.
In the second phase 2030-40 there will be a step change in resilience delivered as well as demand and leakage reduction targets for 2050 to be met. During this time, construction will begin on strategic resource options and an intra-regional transfer. There will also potentially be an effluent re-use scheme in operation and a new reservoir will “likely” be under development.
The third phase, 2040-50, the plan will be adaptive depending on how earlier stages have gone and what environmental impacts look like. At this time, the plan sets out that environmental improvements that need significant investment or have a low benefit to cost ration will be undertaken. The leakage reduction target of 50% will have been met and the plan forecasts per capita consumption (PCC) will lower to 110l/d.
By that stage, reservoirs or large strategic scheme will be online and regional interconnectors will be live.
The first recommended action will be around demand reduction, undertaking these as soon as possible will create headroom in future scenarios. Future works will rely on the success of that strategy with pathways in later parts of the plan dependent on whether water demand is higher or lower than forecast.
WCWRG analysed the types of risks the region was exposed to, together with predictions for future water usage and the types of options available to assess how to best mitigate the risks. It concluded the region has only a rudimentary understanding of non-public water supply needs. It said despite a heavy reliance on demand management, delivery of these remains uncertain. Likewise the strategic water resource schemes have been identified, but are not guaranteed. It said a new strategic resource may be necessary within the next 15 years to meet demand.
The group has launched a consultation period on the emerging strategy that will feed into the draft plan, which is due to be published in the autumn.