Reservoir construction timeline

Havant Thicket Reservoir is being delivered through an innovative partnership between Portsmouth Water and Southern Water.

The current scheme received planning permission in late 2021, with the main construction phase of the project due to get underway in Spring 2024. When completed, we will take water from the reservoir during a drought, allowing us to supply Southern Water with 21 million litres of water a day from our supplies further to the west.

To be clear, the current approved plan for the reservoir has no element of recycled water associated with it.

Planning for the future

As part of work to plan for the future, Portsmouth Water and Southern Water have been exploring additional ways of supplying the region with sustainable sources of water and taking further steps to protect and improve our environment. This has involved looking at different options, including adding highly-treated recycled water to Havant Thicket Reservoir to supplement water levels and enable it to provide more water during drought. Supplementing the reservoir with recycled water would secure up to 90 million litres a day extra.

It’s important to be clear that the water recycling proposals, known as the Hampshire Water Transfer and Water Recycling Project, are subject to further public consultation, as well as approval by regulators and planning permission being required. There's lots of information on Havant Thicket Reservoir and water recycling on the new webpages we've set up on this important issue.

Without pre-empting the consultation and approval process, Portsmouth Water and Southern Water have been looking at how the already approved Havant Thicket Reservoir scheme can be future proofed, by working together to share infrastructure, with an updated planning application for a pipeline link to the reservoir that can be used by both Portsmouth Water and Southern Water.

Our key priority is to minimise disruption to residents and the environment, while delivering the infrastructure needed efficiently and with value for money for customers. A shared infrastructure approach means that, if proposals for water recycling are agreed in the future, residents won’t need to experience additional disruption. It will also reduce environmental impact and it’s estimated that taking this future proofing approach could save over £100 million, compared to installing separate new infrastructure at a later stage.

Water industry regulator Ofwat has been involved in discussions on this approach, and is supportive of it, as it agrees that it’s in the best interests of Southern Water customers (who are ultimately funding the reservoir scheme), the environment and society more broadly.

The two pipelines that would be put in would only initially be used by Portsmouth Water to fill the reservoir with spring water and take water out again - they would not be used for recycled water unless, and until, the Hampshire Water Transfer and Water Recycling Project has received the official go ahead to proceed and has been constructed.

Revised timeline

A new planning application for the Havant Thicket Reservoir pipeline will be submitted to the local planning authorities, with determination of the application expected to be completed in 2024. Regulator Ofwat will then need to approve the planned costs.

This shared infrastructure approach will mean that the reservoir will be finished later than originally planned. When planning and regulatory approvals are in place, Portsmouth Water will confirm the new date for the reservoir to be completed, taking into account the seasonal nature of the required earthworks, that can only take place during dry summer months, as well as the reservoir filling that requires a surplus of spring water in the winter.

However, working in a joined-up way will ensure that we have a future-proofed infrastructure plan for resilient water supplies for customers and protecting the environment - in particular, Hampshire’s precious chalk streams.

The Havant Thicket Reservoir project will be paid for by Southern Water, through its drinking water customer bills. These costs are expected to be spread over many years – to reflect the continued benefits of the reservoir. Portsmouth Water customers are not paying for the reservoir through their drinking water or wastewater bills.