Havant Thicket Reservoir

The South East is ‘water stressed’. The Environment Agency has predicted that 3.5 billion extra litres of water are required by 2050 (50% of the need is in the South East). Although we are water stressed in Hampshire (particularly in the areas covered by Southern Water), we do have an abundance of natural springs and also lay claim to a number of chalk streams - including the Test and the Itchen.

The water companies are now looking at options for securing the water supplies for decades to come, recognising that extreme weather events, such as prolonged droughts and exceptional rainfall, are going to become more commonplace. Lots of options are being considered, but are likely to include repairs/upgrades to pipes to prevent and fix leaks, improved efforts to capture and store rain water, and significant investment in the UK's antiquated sewage system to reduce the number of sewage overflows into our rivers and streams.

It is important to note that there are two project proposals, which get considered individually - the first is to create a reservoir; the second is to 'repurpose' that reservoir as a waste water recycling facility. They are both outlined below; the descriptions of them here are derived in large part from information provided by the water companies. You can see more at: Havant Thicket Reservoir project

The Havant Thicket Reservoir

Hampshire's new reservoir, which is currently being built, is being delivered as a partnership between Portsmouth Water and Southern Water. It is located close to Rowlands Castle and Havant and is due to be operational by 2029. It will cost approximately £340 million to build.

This reservoir will enable Portsmouth Water to capture and store excess rain water over the winter months. This is water that currently runs off into the sea. This water, added to the water from Hampshire's many natural springs, can then be supplied to Southern Water in times of drought so that Southern Water, in turn, can reduce the amount of water it takes from the Itchen and Test chalk stream rivers.

The reservoir will be able to hold 8.7 billion litres of water when full and supply, on average, 21 million litres per day. Portsmouth Water already shares 30 million litres per day with Southern Water. Once the reservoir is operational they will be able to share an extra 21 million litres per day plus an extra 9 million from this year (equal to 60 million litres per day eventually). Southern drinking water customers will see an increase in their bills to pay for the reservoir.

The Water Treatment and Water Recycling (WTWR) project at Havant Thicket Reservoir:

Southern Water have proposed a new water recycling plant south of Havant to turn treated wastewater into recycled water, which would eventually become drinking water. The recycled water would be transported to the Havant Thicket Reservoir via a pipeline where it would be mixed with spring water and subjected to treatments and filtration. A further pipeline would then take this purified water to the Otterbourne Water Supply Works where, following further treatments, including the addition of chlorine, it would be turned into drinking water.

The aim of Southern Water's new plant is to build in more resilience to the challenges posed by climate change and the growing population, and create a sustainable water supply for future generations.

The WTWR would be the first water recycling plant of its kind in the UK, although this technology is in use in other parts of the world. The approximate cost would be £1.2 billion. Southern Water has estimated that the new plant would supply up to 111 million litres per day. Southern Water say it would also mean that they would not have to tap into the local chalk streams during droughts (or ship in supplies from Norway).

Current status of the project:

As mentioned above, the Havant Thicket reservoir and the WTWR are two separate projects. The reservoir has passed the planning stage and is now in the construction phase. The WTWR is at a much earlier stage and still requires permission. Southern Water has recently consulted on the project as part of its draft water resources management plan.

Once Southern has analysed the responses, it plans to apply for a consent order from Defra next year (2025). Defra, as the responsible department, has determined that the WTWR is of national significance meaning that the project will be assessed by the planning inspectorate, rather than the local planning authority.

More broadly, the water regulator, Ofwat, will shortly publish its determination for the water companies (on 19 December 2024). This will tell the water companies what they are allowed to charge customers over the next five years. These prices will be in place from April 2025.

In Parliament:

The WTWR project is a colossal project with wide reaching implications. It's important that we fully understand the environmental impacts of the proposals, and how they will be mitigated, and the business case behind the project. To that end, I've started asking questions in Parliament to try and get a better sense of the government's view on the concept of water recycling at Havant Thicket. I've tabled a number of Parliamentary Questions on the government's assessment of the concept of water recycling and transfer, as well as on the specifics of the water recycling scheme at Havant Thicket, and on the regulatory/approvals processes. A sample of the responses from the Defra Minister is below. I've also requested a debate on the proposals.

Question 1 (tabled on 18 November):
To ask the Secretary of State for Environment, Food and Rural Affairs, what recent discussions he has had with the Water Commission on the proposed water transfer and recycling project at the Havant Thicket Reservoir. (14597)
Emma Hardy:

The independent water commission, led by Sir Jon Cunliffe, will consult experts in areas like the environment, public health, engineering, customers, investors and economics, reporting to the Secretary of State for Environment and Wales’ Deputy First Minister and Cabinet Secretary for Climate Change and Rural Affairs by Q2 2025. The commission will consider the challenges the water sector faces as a whole and use the evidence to set out recommendations that will help transform the sector. The Terms of Reference for the Independent Commission are available at GOV.UK.

Question 2 (tabled on 18 November 2024):
To ask the Secretary of State for Environment, Food and Rural Affairs, what guidance his Department issues on criteria for approval of a water transfer and recycling project. (14599)

This question was grouped with the following question(s) for answer:

To ask the Secretary of State for Environment, Food and Rural Affairs, what assessment he has made of the potential (a) merits, (b) risks and (c) cost to the public purse of the proposed water transfer and recycling project at the Havant Thicket Reservoir. (14595)
To ask the Secretary of State for Environment, Food and Rural Affairs, whether he has made an assessment of potential impact of the proposed water transfer and recycling project at the Havant Thicket Reservoir on Hampshire’s chalk streams. (14596)
To ask the Secretary of State for Environment, Food and Rural Affairs, whether he has made an assessment of the potential relevance of international comparisons of the potential (a) merits, (b) risks and (c) costs of proposals for recycling waste water in (i) Havant Thicket and (ii) elsewhere. (14598)

Answer (Emma Hardy):

Southern Water are currently consulting on their Water Resources Management Plan (WRMP), which includes the proposed water transfer and recycling project at Havant Thicket Reservoir. Water regulators will review and scrutinise the plan to ensure it is fit for purpose, the risks to the environment including the impact on chalk streams are low, and it is value for money.

Options such as water recycling mark a transition to water supplies that are not dependent upon the uncertainties of rainfall. These options are well established elsewhere around the world and in the UK, to ensure resilient supplies in a changing climate.

For any water recycling scheme to proceed it must comply with the Water Environment Regulations (formally the Water Framework Directive) and the Habitats Regulations. The Environment Agency will ensure environmental requirements are met through their roles as statutory consultee of the planning process and regulator for environmental permits. Environmental impact assessments are required to support planning and permitting and appropriate mitigation must be provided for any impacts.

Question 3: To ask the Secretary of State for Environment, Food and Rural Affairs, if he will (a) commission an independent assessment of the potential (i) environmental and (ii) health impact of using recycled waste water and (b) pause approval of water (A) transfer and (B) recycling projects until that assessment is published. (21 November 2024)

Answer (Emma Hardy): For any water recycling scheme to proceed it must comply with the Water Environment Regulations (formally the Water Framework Directive) and the Habitats Regulations. The Environment Agency will ensure environmental requirements are met through their roles as statutory consultee of the planning process and regulator for environmental permits. Environmental Impact Assessments are required to support planning and permitting and appropriate mitigation must be provided for any impacts.

Water re-abstracted from the environment for public water supply must also be treated to meet our high drinking water standards before use, in accordance with a robust risk assessment. Recent research carried out for the Drinking Water Inspectorate indicated a high level of support (79% agreement) for the use of water recycling to supplement drinking water supplies.

There are currently no plans to commission an independent assessment on the potential of using recycled waste water.

The full list of my written ministerial questions to Defra can be found here.

Local concerns:

There are very legitimate concerns in the community and from environmental groups about these proposals. Over the coming months I will be scrutinising the Southern Water proposals and continuing to push the government to provide answers to a number of essential questions about the scheme - not least, what are the pros and cons of water recycling over other schemes to improve water resilience?

To tell me what you think about the proposals, please use the 'Contact' link at the top of the page.