Frequently asked questions

Anglian Water, working in partnership with Cambridge Water, is proposing a new reservoir in the Fens that will secure water supply to our customers for future generations.

You can play an important role in helping to shape our proposals, so they best serve the needs of everyone.

Below are some answers to questions that have been most frequently asked during our first phase of consultation.

Anglian Water, working in partnership with Cambridge Water, is proposing a new reservoir in the Fens that will help secure water supply to our customers for future generations.

The proposed new reservoir will help to secure water supplies for the region, while protecting the environment from the effects of a changing climate.

It will store water so it’s on tap when we need it, helping us meet the challenges of a changing climate and a growing population. It will mean less water is taken from sensitive sources, helping us to protect and restore the environment.

We expect the reservoir to enable wider social, environmental and economic benefits too. Just like our existing reservoirs such as Rutland Water and Grafham Water, the new reservoir could be a valuable leisure destination. It could also support and conserve wildlife and biodiversity, and provide a variety of places for people to explore, learn and get closer to nature.

The proposed new reservoir in the Fens will have a water surface area of approximately 5km² - around the size of Grafham Water - and hold up to 55 million cubic metres of water. It will have the potential to supply up to 87 million litres of water a day for up to 250,000 homes a year.

We’re in the driest region in the UK, making us particularly vulnerable to climate change impacts. This is creating greater stress on water resources with incidents of extreme weather forecast to increase.

Our region is one of the fastest growing in the country. It is estimated that there could be more than 175,000 new homes built over the next five years. By 2050, the region’s population may grow by a further million people.

To meet these challenges, we all have to play our part in balancing the needs of society, business, and the environment to enable a sustainable future.

We’re already working on new strategic pipelines to move water from wetter to drier parts of our region, installing smart meters in customers’ homes, and driving down leakage. While all the investments we’re making today will help to keep taps running, the available supply will fall well below the demand for water unless we plan for future resources now.

This proposed new reservoir has been identified as a large-scale investment in new water resources that we need and will play a critical role in securing water supply long into the future.

Reservoirs contain a volume of water that provides a level of resilience and environmental opportunities that are not provided by other resource options such as desalination or water reuse. They store excess river water from wetter winter periods, when flows are at their highest, for use in dry summers when water is more scarce.

This enables us to make the most of wet weather so that we can continue to service our customers during periods of dry weather. It also reduces the reliance on ground water sources, which in turn enables ground water recovery, such as to chalk streams.

When we looked at where we might best build reservoirs across our broader region, we identified rivers in the Fens areas as having enough water surplus in the winter to supply the reservoir.

The proposed new reservoir will help us give sufficient water to enable resilience to future droughts, while protecting our most sensitive environments.

It will make the most of the available resources and provide water to local communities and businesses in Cambridgeshire and across our region.

We completed a multi-stage site selection process. This aimed to make sure we identified a location that would be suitable for hosting a reservoir. Through the process we also sought to minimise impacts on nearby areas and communities, and meet planning and regulatory frameworks.

Looking across a broad search area we identified a large number of potential locations and assessed their performance against a range of factors. Geology and geography play a significant role in selecting a site for a reservoir; equally we needed to exclude areas of land where the reservoir could not be located due to existing restrictions or protections. The site locations that performed best at each stage were taken forward and assessed again, in more detail, against a range of criteria. A sequential test was carried out during the third stage of our site selection process too, to prioritise locations that carried the lowest level of flood risk.

You can read full details about this process in our site selection report.

Site Selection Report

This location was found to be the most appropriate for building a new reservoir during our site selection process. On balance, it performed best across a range of the key factors we assessed. It also provides the potential opportunities to deliver wider benefits to the regional economy and neighbouring communities.

You can read more about how we made these conclusions in our site selection report.

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Yes, quality of agricultural land and potential impacts were considered in the site selection process. Given the size of the reservoir, all of the sites we have considered had the potential to effect agricultural land.

The site we’re proposing was the best performing of all the sites we have considered – one which balances all of the factors we considered, and that also provides significant opportunities to unlock wider benefits.

We are committed to supporting those affected by our proposals as the project develops. One of the ways we plan to do this is through a residential property support scheme, which could offer support to homeowners who would like to sell their properties before the project has consent and acquisition of property commences.

While Anglian Water and Cambridge Water are not required to do this, we think it is an important step in providing support for people most affected by our plans for the reservoir in the Fens.

The residential property support scheme is currently being developed and we will share more details in our next consultation in 2024. In the meantime, we’re in close liaison with those directly impacted.

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We completed a multi-stage site selection process (outlined in the link below) that considered a wide range of factors, including geology, engineering requirements and impacts on the community.

In total, we considered 81 potential sites around Cambridgeshire and have identified the preferred site as the best performing. It is currently the only site we’re considering.

While site location was not a specific part of the phase one consultation, any suggestions for alternative sites in consultation feedback will be reviewed against the same criteria, and to see if we have considered them already.

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It is proposed that water will be abstracted from the River Great Ouse catchment when river levels allow. This will be supported by a piped transfer. The water stored at the reservoir will then be treated and transferred so it can be supplied to Anglian Water and Cambridge Water customers.

The location of the supporting infrastructure needed to move the water to and from the reservoir is not included in this consultation. We will provide our proposals for these facilities in future consultations when we will seek your feedback.

The reservoir is part of our long-term plan to ensure we can continue to deliver enough water to local communities and businesses across our region, including in Cambridgeshire.

You can read more about the two company's plans for managing water resources and the background to our investment in infrastructure in our Water Resources Management Plans. You can find Anglian Water's WRMP, and Cambridge Water's WRMP below.

Anglian Water's WRMP Cambridge Water's WRMP

The reservoir's capacity has been determined by the Water Resources Management Plan process. This is the process water companies follow to identify what we need to do to secure water supply for our customers long-term.

Without long-term planning, there will simply not be enough water to supply our customers in the future, despite our leadership in leakage and resilience, and decades of hard work and investment in this area already.

Anglian Water and Cambridge Water’s current Water Resources Management Plans assess what we both need to do by 2050, taking into account increasing demands due to population growth, environmental needs and the climate change challenges facing water security.

The reservoir - including its capacity - has been identified in both plans as a crucial investment that we need to make to secure supplies for the future. You can read Anglian Water’s WRMP and Cambridge Water’s WRMP by clicking the relevant button below.

Anglian Water's Plan Cambridge Water's Plan

The reservoir would be funded by water company customer bills, with a third-party provider likely to construct and operate it.

This funding model is common on other nationally significant infrastructure projects and Ofwat, the water industry regulator, is keen that we explore similar options for the Fens reservoir.

We will provide more detail on this as the project develops.

Due to the storage capacity of the reservoir, the project is classified as a Nationally Significant Infrastructure Project (NSIP). This means we need to make an application to the Planning Inspectorate for a Development Consent Order (DCO). The Planning Inspectorate will issue a recommendation to the Secretary of State who will then make a final decision as to whether the project is consented. We expect to make an application in 2025, and for the Secretary of State to make a decision by 2027.

The feedback we receive from local people and all our stakeholders is key to making sure we develop the reservoir to keep impacts as low as possible, and create benefits for people and nature. All feedback from our first consultation has been reviewed, recorded and is carefully being considered as we refine our proposals. This will also be the case for feedback received during future rounds of consultation.

There are some aspects that are not open to influence. That’s because they cannot be shaped for technical reasons, such as safety and engineering requirements, or because they have been and continue to be established and consulted on through other statutory processes. This includes the project’s need case, and the capacity of the reservoir, which are both set by the Water Resources Management Plan process.

If consent is granted to build the reservoir, construction could begin in around 2029-2031, with the expectation that it would start supplying water to customer taps from the mid to late 2030s.

Throughout the site selection process, we have been working with environmental organisations such as the Environment Agency and Natural England.

High-level environmental assessments were also undertaken as part of the site selection process. You can read about these in the site selection report, available on our website below.

Our Environmental Impact Assessment (EIA) will continue to be a key part of how we develop plans for the reservoir, and is central to the planning process we’re following.

Environmental surveys will begin in the coming months. The results will influence the project development and design proposals as we move towards the next phase of consultation.

The findings of our EIA work will be consulted on as part of our Preliminary Environmental Information Report (PEIR) and presented in an Environmental Statement which will accompany our application for consent. The scope of these studies will be agreed with the Planning Inspectorate as part of the formal EIA scoping process.

Through these processes we will investigate the potential environmental impacts of the proposed project, together with how we plan to reduce or limit these impacts.

Site selection report

Minimising flood risk was a central part of our site selection process and will be key to the design of any new reservoir. A sequential, risk-based assessment of flood risk was used to ensure that only sites that carried the lowest level of flood risk made the final short list of sites.

Measures will be put in place to ensure the reservoir will not increase the current risk of flooding. We also believe there are potential opportunities to explore with partners for the reservoir to improve the flood risk in the area. Our site selection report (available below) highlighted potential opportunities for surrounding communities, including expansion of the Cranbrook and Counter Drain.

Site selection report

We are designing the reservoir in line with the latest industry guidance and standards, and following the legislation set out in the Reservoirs Act 1975. This includes requirements for emergency planning – such as the ability to lower a reservoir’s water level quickly (‘drawdown’) in the event of an emergency. Using an emergency drawdown is a highly unlikely event, but nevertheless a clear plan for managing emergency situations where this might be required is a vital part of developing projects like these.

We’re at an early stage of considering how emergency drawdown facilities might operate. Initial modelling has confirmed that discharge to the existing river network is a viable option for this, and will mitigate the already low risk of flooding to the local community.

As part of the Environmental Impact Assessment (EIA) we will thoroughly investigate the potential environmental impacts of the emergency drawdown solution that is chosen.

Plans for the emergency drawdown will be consulted on during future phases of consultation.

We recognise the importance of connectivity between the settlements that surround the site. We’re at a very early stage of our proposal, and the finer details of the design will continue to evolve as we refine these plans based on further studies and consultation feedback, but we will ensure we maintain connectivity between settlements.

It is too early to say exactly what the impact on the surrounding road infrastructure might be, and how and where the site might be accessed. We will be seeking to avoid or minimise impacts where that is possible. These will be matters for discussion and development as part of future phases of consultation.

We understand the need to minimise the potential impact of vehicle movements associated with the construction of the reservoir and we also recognise people want assurance that construction traffic will not cause damage.

Our engineers will be developing plans to help support road infrastructure as part of our proposals, which we’ll provide at future stages of consultation.

We’ll also be working closely with the Fenland District Council and Cambridgeshire County Council to seek their input.

The potential height of the embankments against the adjacent ground level will vary around the reservoir dependent on final design and could be potentially up to 20 metres in places. The illustrative concept plan for the reservoir presented in our consultation brochure shows an embankment of approximately up to 20 metres.

The embankments will be new features in the landscape. We are looking at ways to reduce their potential prominence and be considerate of the surrounding landscape character in our proposals, and are taking landscape, ecological and stakeholder feedback into account as we develop the design.

Our approach could include altering the shape of the reservoir edge or making the slopes less uniform, by varying the profile and gradient at different points around the reservoir. At the moment, we anticipate the reservoir will have an average slope rate of around 1 in 10. This means it would gain a metre of height for every 10 metres of length on average, which is relatively gentle.

Anglian Water’s leakages rates per kilometre of water main are half the industry average, despite having the biggest geographical region of any water company.

We have been working hard to reduce leakage in our network - it’s the lowest in the industry per kilometre of pipe and we’ve exceeded our targets on leakage for more than 10 years in a row.

Last year we delivered our best ever performance, surpassing the incredibly stretching target set by our regulators Ofwat, and delivering the equivalent of five years’ worth of reduction in a single year.

But we’re always looking to push it even further, and we are committed to making a 16.4 per cent reduction in leakage before 2025.

These levels of leakage haven’t been achieved before in the UK or, as far as we know, globally. While these targets are ambitious, we are confident that we can achieve them – in the last financial year we surpassed our target of a 5.4 per cent reduction, delivering a 6.1 per cent reduction by finding and fixing more than 37,000 leaks.

We are proud of our record in reducing leakage. However, our Water Resources Management Plans make it clear that alongside tackling leakage we also need to invest in the supply-side to increase the amount of water available. Our new reservoir in the Fens is central to those plans.

We were pleased to share our early proposals for the reservoir with communities and stakeholders in our first phase of consultation in autumn 2022, and we are grateful to everyone that provided feedback.

It was great to talk to local people and stakeholders to understand their thoughts and comments. It is clear they see great value in the environmental and recreational benefits the reservoir could bring and are excited by what it could mean for the region.

At the same time, people shared their concerns about a wide range of topics and potential effects on local communities and roads in the area. The local community also want to know what this will mean for the people whose homes, land or business may be affected by our plans.

We have now published a summary of the feedback we received during our first phase of consultation, which is available below. The feedback is now being used to inform the development of the project, ahead of a second phase of consultation in 2024.

View summary

The Regulators’ Alliance for Progressing Infrastructure Development (RAPID) assesses proposals for new large-scale, strategic investments to make sure water companies are progressing options that best meet their customers’ needs. RAPID is a non-ministerial government department and is made up of the three water regulators – Water Services Regulation Authority (Ofwat), the Environment Agency (EA) and the Drinking Water Inspectorate (DWI).

The four-stage RAPID gated process relates to funding the development of water resource solutions. At each gate, companies submit information about their work on a solution, which is assessed by Ofwat and RAPID to ensure they are making progress.

RAPID’s assessment is carried out when companies submit information about their proposals at points in time called ‘gates’. There are five gates in total, and RAPID decides at each one on the level of funding that water companies should get to help them further progress their projects.

We submitted our gate two report for the Fens Reservoir in November 2022. RAPID has granted funding for us to continue to progress our proposals until a conditional review point in January 2024, before our gate three submission in Autumn 2024. This is so RAPID can consider the evidence as to whether the project is providing the best-value solution to meeting water needs. It also allows us to explore potential possibilities to increase the amount of water supplied by the reservoir.

The conditional review, to be held in January 2024, will confirm whether the project continues to progress through the RAPID process. We are confident that we will be able to evidence that the project provides a best value solution.

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Get in touch

Contact the project team today.

Freephone: 0800 915 2492


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