A new study for the Regulators’ Alliance for Progressing Infrastructure Development (RAPID) has identified potential new water transfer options to address the growing water supply water deficit which is projected 3,435 million extra litres of water per day to reach by 2050.

In 2019 RAPID and Ofwat recognised that a national-scale tool that enables identification of potentially cost-efficient combinations of water supply options and water transfers in England and Wales could be in the public interest.

The National Framework for Water Resources published in March 2020 by the Environment Agency identified a deficit of 3,435 million extra litres of water per day (3,435 Ml/d) in England by 2050 if no new water infrastructure development occurs between 2025 and 2050.

The University of Manchester carried out the project as part of RAPID’s effort to accelerate the development of new water infrastructure and design future regulatory frameworks in England and Wales. RAPID is aiming to identify cross-company strategic water resource options that help meet water demands over the next 5–15 years and beyond.

RAPID also aims to facilitate the coordinated development of these Strategic Resource Options (SROs) so that they are in the construction stage by 2025–2030 and can increase the resilience of national water supplies.

The project builds on and uses a tool able to identify efficient mixes of future supply and transfer options nationally using existing water company data.

The supply-demand model includes local water supply options and transfers documented in the water companies' Water Resource Management Plans 2019 (WRMPs). This includes transfers that were considered feasible by water companies but not included in water company plans and new water transfers not in company plans.

Model chooses from over 4,000 water supply options

The model has used cost information from the WRMP19 plans to help identify cost-effective portfolios, choosing from over four thousand water supply options.

The researchers say the model’s consideration of thousands of potential new transfers (those not previously scoped or included in plans) is necessarily simplified due to the lack of more detailed information.

Instead, the model identifies portfolios of potentially cost beneficial options for further exploration in more detailed work being carried out by regional groups and water companies.

The model includes existing water transfers and potential future transfers which fall into three categories:

1. preferred transfer links according to a list of company transfers that companies plan to implement after 2025;
2. feasible transfers which companies have considered, but do not appear in the current published company water resources plans; and
3. possible future transfers between neighbouring Water Resource Zones (WRZs).

Preferred and feasible sets of transfers and local supply options in WRMP19 plans "insufficient to avoid a deficit by 2050"

The findings suggest that the preferred and feasible sets of transfers and local supply options considered by companies in their WRMP19 plans are insufficient to avoid a deficit by 2050 under challenging demand, drought resilience and environmental scenarios (consumption set at 118 litres per person per day; 1 in 500-year drought resilience; environmental sustainability reductions set to 721 megalitres per day).

Under this scenario, large deficits occur in Thames London and Severn Trent Strategic Grid, with lower deficits in the East and South East, whereas surpluses occur in the North and the northern part of Water Resources West.

"Planning at England and Wales scale" could potentially decrease total water supply costs "by up to 24% compared to current company plans"

The report says:

“Greater collaboration, through the use of inter-regional transfers, has the potential to reduce total costs and help balance supply and demand. This supports the case for strategic planning beyond individual water company boundaries as the regional groups are currently doing…..

“Results suggest that planning at an England and Wales scale and exploiting new potentially cost-efficient connections decreases total water supply costs including transfer cost by up to 24% compared to current company plans; 9% of that cost reduction is due to being willing to transfer water between regions.….

“The observed patterns of local supply and transfer investment appear to be significantly driven by meeting demand in London and South East England.”.

The report says that through seeking efficient solutions at an England and Wales scale, the model can meet higher demands, including for the environment in the form of reduced abstraction, at higher service levels at a cost similar to currently planned water supplies.

However, the researchers caution that selection of transfers is sensitive to the requirements for treatment, and the further costs that treatment implies.

The model is sensitive to the cost of local supply options - since the costs of options vary considerably between companies, further investigation might be warranted of these costs, the researchers say. Severn Trent Strategic Grid and Thames Swindon and Oxfordshire (SWOX) had the most low-cost options.

The general large-scale pattern of water transfers from north to south in the model is:

1. Surplus water from United Utilities Strategic Resources Zone to Severn Trent Strategic Grid, with the Vyrnwy-River Severn transfer prominent.
2. Severn Trent Strategic Grid builds relatively cost-effective supply options, from which water is transferred to Water Resources East and Water Resources South East (WRSE).
3. Water transferred to WRSE (Thames SWOX) is through the River Severn and a permutation of the Deerhurst to Culham transfer.
4. Abingdon reservoir supplements water in Thames SWOX before a transfer is sent to Thames London.
5. London has a large 300 Ml/d deficit under the National Framework central scenario but does not develop a significant amount of local supply capacity in the most cost-effective portfolios (only 125 Ml/d).

Options to be followed up by regional water resources groups

The report has identified a number of issues it suggests should be followed up by the five regional water resources groups, including:

Water Resources North (WRN)

There appears to be a lack of preferred and feasible transfer options to allow access to surplus water from Kielder reservoir. The distance between WRN and areas that require the water increases the costs of possible transfers. However, the region should explore whether there are viable low-cost transfer options to connect WRN to WRW or WRE.

The model recommended few cost-effective inter-regional transfers originating from WRN. Potential transfers, such as between Yorkshire Water Grid Surface Water Zone and Anglian Water Central Lincolnshire in WRE, should be explored further to test whether cost-effective transfers can be found.

Water Resources East (WRE)

The identification of many short, low-capacity transfers by the model as cost-effective in WRE indicates a lack of local supply options to meet demand under high resilience and sustainability reductions. The region should consider whether there are additional cost-effective local supply options in the WRE area that can be proposed by regional groups or water companies.

The model indicates the potential to transfer water from WRW to WRE using the existing canal network. This should be further explored.

The model recommended an inter-region transfer from WRE to WRSE supported by raising the reservoir on the Great Ouse. This result was because the model used an adjusted cost dataset where this option was cheaper than the Grand Union Canal reuse option. The relative benefits of these options should be considered further.

The South Lincolnshire Reservoir and the raised reservoir on the Great Ouse appear to be important local supply options in the context of this modelling.

Water Resources South East (WRSE)

The deficit in Thames Water (TW) London under the preferred and feasible transfers and more challenging scenarios (per-capita consumption, resilience and sustainability reductions of 118 l/h/d, 1:500 and 721 Ml/d, respectively) indicates a need for additional local supply options and/or transfers to be considered by companies.

The identification of many short, low-capacity transfers by the model in WRSE as being cost effective potentially indicates a lack of local supply options to meet demand under more challenging scenarios (per-capita consumption, resilience and sustainability reductions of 118 l/h/d, 1:500 and 721 Ml/d, respectively). The region should consider whether there are additional cost-effective local supply options in the WRSE area that can be proposed by regional groups or water companies.

Meeting the deficit in London using the options available to the model appears to depend largely on inter-region transfers from WRW along the River Severn and Thames, supported by the Vyrnwy and Abingdon Reservoirs.

The preferred inter-region transfer between WCWR and WRSE appears to be important in the context of these model runs and the selection of an additional possible transfer by the model as cost effective indicates theoretical benefits from expanding this option.

West Country Water Resources (WCWR)

The model recognises transfers between WCWR and WRSE as being cost effective in addition to those considered as preferred and feasible by companies. This suggests that there are theoretical benefits from either increasing the capacity of company-considered transfers to WRSE or identifying additional transfers.

Water Resources West (WRW)

The surplus in United Utilities (UU) Strategic Resource Zone under more challenging scenarios (per-capita consumption, resilience and sustainability reductions of 118 l/h/d, 1:500 and 721 Ml/d, respectively) indicates further potential for transfer of water to Severn Trent (ST) Strategic Grid beyond the preferred and feasible transfers.

The deficit in ST Strategic Grid under more challenging scenarios (per-capita consumption, resilience and sustainability reductions of 118 l/h/d, 1:500 and 721 Ml/d, respectively) and under the preferred and feasible transfers indicates a need for additional local supply options and/or transfers to be considered.

ST Strategic Grid appears to be an important WRZ for inter-region transfers to WRSE and WRE. In particular, the transfer to WRSE along the River Severn supported by the Vyrnwy Reservoir appears to be key to meeting the deficit in London.

Many of the inter-region transfers from WRW to WRE use the existing canal network. The potential for using the canal network should be fully explored.

Wales appears to have insufficient supply options to enable meaningful transfers east. However, there may be cost-effective local supply options that companies could consider.

Important local supply options, in the context of these model runs, appear to include the Carsington Reservoir support to Melbourne WTW, the River Soar to support Cropston WTW and the Birmingham BHs conversion to potable supply.

"Model could be used in future to bring national perspective to identification of potentially efficient transfer and supply options"

The report suggests that the model’s data and a library of results could be made accessible (explorable and updatable) online and shared with a designated group to encourage experimentation and exploration of future designs by a group of authorised users.

The model could be used in future along with a water transfer database that companies, regional groups, regulators and navigation authorities could share, update and collaborate on for joint use.

“The model, if developed further, could potentially be used more formally in future as a way of bringing a national perspective to the identification of potentially efficient transfer and supply options,” the report says.

Click here to download the full report A water supply-demand model for England and Wales - Report to RAPID