Leakage work remains a key priority.

For the third consecutive year we have beaten our annual leakage target, and over the last five years leakage has been reduced by 26 per cent.

However, fixing all the leaks won't save enough water in the long-term, and new resources, including the proposed Upper Thames Reservoir, will be required.

Our previous consultation on the design of the reservoir (at Stage 2), envisaged a reservoir that could hold 150 million cubic metres. The draft Water Resources Management Plan currently includes a slightly smaller reservoir, with a capacity of 100 million cubic metres.

 Find out more about our Water Resources Management Plan

However there are considerable uncertainties - for example, about the scale of future water demand and the depth and duration of the economic recession.

We therefore anticipate that the reservoir would be somewhere between 100-150 million cubic metres.

To put that volume of water into context, 150 million cubic metres is equivalent to 150 billion litres or 33 billion gallons. The surface area of the water would be about 6.7 km2 or 900 football pitches.

The site south-west of Abingdon, Oxfordshire, is preferred for a reservoir at all sizes from 50 million cubic metres and above.

Two or more sites in combination would increase the likely environmental impacts of development. To create the same storage volume using several smaller sites would require a larger area of land in total and consequently greater construction impacts.

The reservoir site selection study identified sites at a range of sizes from 30 to 150 million cubic metres. The site south-west of Abingdon, Oxfordshire, is preferred for a reservoir at all sizes from 50 million cubic metres and above.

The depth and duration of the economic recession, new climate change scenarios and the possibility of reductions in our existing abstraction licences on environmental grounds, mean that our plans are constantly evolving.

Previous calculations suggested a reservoir with a capacity of 150 million cubic metres would be required by 2021, and more recently a reservoir with a capicity of 100 million cubic metres by 2026.

We will monitor these factors closely and any changes will be reflected in our Water Resources Management Plan, which is reviewed annually.

 Find out more about our Water Resources Management Plan

We examined the whole of the River Thames catchment and identified 55 potential reservoir sites.
A wide range of criteria was used to rule out sites, including:

• International and national sites of nature conservation importance
• Landscape character
• Archaeology
• Loss of flood plain
• Impact on the local residential environment
• Opportunity for construction material and transportation by rail

The site near Abingdon came top of our assessments. The site's strengths are:

• It is reasonably flat land
• It has the right ground conditions for a reservoir
• It is close to a river
• It is not heavily populated
• An adjacent railway and major road links could be used to deliver construction materials.
• It is well placed to serve the needs of customers in Swindon, Oxfordshire and London.

Water would be taken from the river and stored in the reservoir.

For supply to Swindon and Oxfordshire, water would then be treated and put into the local mains network.

For London, water would be released back into the river, and stored in our London reservoirs downstream.

Guidance from the Environment Agency on when we can take water from the River Thames indicates that there would be sufficient water to fill and operate the reservoir.

At the appropriate time, we would submit an application for consent in accordance with the relevant legislation that is in force at the time.

Currently, we expect this to be an application to the Infrastructure Planning Commission, as the reservoir would be classed as a nationally significant infrastructure project.

Approximately £1billion.

Investment is largely paid for with company loans.

The repayment of these loans is then funded by money received from all customers' bills.

We have carried out a number of consultations with local people, organisations, regional and national bodies.

We consulted on the need for water, including alternatives, and reservoir site selection (Stage 1), the possible design, conservation and recreation (Stage 2) and more recently on our draft Water Resources Management Plan.

 Find out more about our Water Resources Management Plan

If built, there would be opportunities to provide benefits for recreation, access to the countryside, and new habitats for wildlife.

As the outer embankment would form a large part of the reservoir, it is important to consider how it would be integrated into the surrounding landscape.

An Environmental Impact Assessment (EIA) would be carried out when a more detailed design for the reservoir has been developed following consultation.

An EIA is the process of compiling, evaluating and presenting all the significant environmental impacts of a proposed development. Once all the impacts have been assessed, we would then look at ways to reduce or minimise those impacts.

We would then produce an Environmental Statement which would set out all the processes and ways in which we would address such issues.

For example, during construction, lorries delivering to the site would only be permitted to leave and enter the site directly to and from the A415 Marcham Road via the A34. They would not be allowed to drive through Marcham village or any other local settlements.

Additional traffic on the A34 generated by the construction and use of the reservoir is likely to be small compared to forecasts of other traffic using the road.

This additional traffic would also likely to be predominantly during off-peak periods. Construction of the reservoir is anticipated to have little impact on traffic conditions on the A34.

Building the reservoir would result in the loss of some of the existing natural flood plain, which protects against river flooding. A new area of flood storage would therefore be needed to compensate for this.

The Environment Agency would require that this flood storage be replaced on an equivalent basis, meaning there would be no net loss of flood plain.

If any householder or landowner believes that they are adversely affected by the reservoir proposals they should contact us to discuss the problem.

We would also recommend that they seek independent professional advice.

We will consider requests for purchase on a case-by-case basis.

Construction time would be dependent on the size of the reservoir. A reservoir of 150 million cubic metres would take approximately eight years to build (and up to a further two to fill it), while a reservoir with a capacity of 100 million cubic metres would take about a year less overall.

The reservoirs that are similar in terms of size, catchment and facilities are: Bewl Water, Grafham Water and Pitsford Water.

Farmoor Reservoir is the closest geographically.

Carsington Reservoir and Rutland Water are much larger and have more facilities and attractions than we are proposing. However, you may be interested in looking at their websites, which are listed below.

Please follow the links for more information:

 Bewl Water

 Grafham Water, Rutland Water & Pitsford Water

 Carsington Reservoir

 Farmoor Reservoir

Because the project has been put back for up to five years the panel has temporarily been suspended.

Water Resources Management Plans cover 25-year periods. Planning over a long period of time is challenging and we must consider many factors.

These include changes to water use, the weather, anticipated climate change, legislation, population predictions and economics.

Therefore, the process must remain flexible and under regular review which sometimes results in changes to the overall plan.

 Find out more about our Water Resources Management Plan

Please contact us and we will be happy to assist.