FAQs
West Berkshire Groundwater Scheme (WBGWS)
What is the West Berkshire Groundwater Scheme?
The West Berkshire Groundwater Scheme (WBGWS) is a groundwater pumping scheme owned and operated by the Environment Agency in response to drought conditions. It was commissioned in the 1970’s as a drought augmentation scheme for Thames Water. Its primary use is to add groundwater into the River Thames via some of its tributaries during periods of drought. This water is then abstracted by Thames Water further downstream in the lower River Thames to become part of the public water supply for London.
The scheme consists of 32 pumping stations (licensed abstraction boreholes) connected to 10 outfalls through 87km of pipeline across West Berkshire. An outfall is an outlet in the system that delivers water to the river. The boreholes are grouped into seven wellfields (Lambourn, Shefford, Winterbourne, Upper Pang, Lower Pang, Enborne and Loddon) abstracting groundwater from the Chalk and Upper Greensand aquifers.
During drought, Thames Water can request us to operate the scheme as part of their Drought Plan.
Why was the WBGWS built?
Following severe droughts in 1943 and 1944, the Metropolitan Water Board investigated ways to meet London’s demand for water. The board proposed taking water from the ground and using it to increase the amount of water in tributaries flowing into the River Thames. Following this proposal, the WBGWS was built in the 1970’s.
Why are we operating the WBGWS now?
The Thames area is currently in drought. July was the driest month in Thames area since records began in 1891.
Thames Water has seen large increases in water demand from their customers through the summer and rapid storage loss in their West London supply reservoirs. They have activated their Drought Plan and have implemented a Temporary Use Ban (more commonly known as a hosepipe ban) from 23 July 2026. They are carrying out actions in their Drought Plan to support public water supplies, including the request to the Environment Agency to operate the WBGWS.
Thames Water has requested that we operate the scheme to support their abstraction for public water supply on the lower River Thames where some water supply reservoirs have fallen to low levels. As part of operating the scheme we carry out enhanced monitoring of the environment including groundwater levels, river flows and groundwater and river water quality.
When and where are we planning to operate the WBGWS?
We started operation on 24 August 2026. This included the initial phased switch on of the Pang, Enborne and Loddon wellfields. We have since switched off the Enborne wellfield on the 30 September.
We have no plans to resume abstraction from the Enborne wellfield, this is to help groundwater levels recover.
We are currently supplying 30 mega litres per day to the River Thames to support Thames Water abstractions for public water supply. Use of the remaining 3 wellfields (Lambourn, Shefford and Winterbourne) is not currently planned as part of this phase but will be kept under close review in the coming weeks as the drought develops.
We plan to operate the scheme until Thames Water's London reservoir storage recovers to acceptable levels. This is largely dependent on future rainfall levels and water demand over the coming weeks and months.
What will you notice?
You may notice increased river flows above the current low levels in the River Pang, lower Foudry Brook, lower River Kennet and lower River Loddon.
Our role is to strike the right balance between supporting public water supplies and protecting the environment. That's why we have enhanced our programme of groundwater, river flows and water quality monitoring. You will see our staff out in the area recording data, and monitoring river flows and collecting water samples, while the scheme is in operation.
How can I find out more?
You should report any incidents to our Incident Hotline on 0800 80 70 60.
You can contact our Drought Team by emailing drought_THM@environment-agency.gov.uk or via Environment Agency general enquiries 03708 506 506 (Mon-Fri, 8am–6pm) or enquiries@environment-agency.gov.uk.
Farmoor Reservoir drought permit
What does a drought permit allow a water company to do?
A drought permit is a temporary permission that allows a water company to take additional water or operate outside the normal conditions of its abstraction licence during a drought. It is intended to help maintain public water supplies when water resources are under severe pressure.
What are the benefits of a drought permit?
A drought permit helps maintain public water supply during drought conditions. It also reduces the risk of further, more severe water restrictions having to be put in place, by allowing water companies to use available water resources more efficiently.
Will a drought permit put additional stress on ecosystems that are already struggling because of this prolonged period of dry weather?
A drought permit is intended to balance the competing needs of protecting public water supplies, while protecting the environment as far as reasonably possible.
Before we grant a permit, we require environmental assessments and we consider whether the impacts are acceptable, what mitigation measures can be put in place, and whether the benefits to public water supply outweigh the temporary environmental risks.
How are the impacts of a drought permit monitored?
We will specify what the monitoring requirements will be as part of granting any drought permit. We usually monitor impacts through a combination of environmental monitoring, operational monitoring, and regulatory oversight.
What is Thames Water doing to help find the additional water supplies they need?
Thames Water has considered alternative supply options as part of their drought permit application and in line with their drought plan. These options include optimising existing sources, use of the company’s strategic schemes, importing supplies from other companies, recommissioning disused sources and other drought permits. The company is keeping its network, treatment and sourcing and supply strategy under constant review to optimise the supply of water.
Why is the West Berkshire Ground Water Scheme (WBGWS) not providing enough water for abstraction?
The WBGWS is currently operated to support flows in the lower reaches of the Thames, enabling additional abstraction to support public water supplies in London. However, it does not provide water directly to Farmoor Reservoir or into the Swindon and Oxfordshire supply zone supported by Farmoor. The Farmoor drought permit is therefore required to enable additional abstraction into Farmoor Reservoir to maintain supplies to Oxfordshire and Swindon.
Will there be further restrictions on public/business water use as well?
Demand management is equally as important as supply management and is considered as part of Thames Water’s drought plan. Thames Water currently has enhanced water efficiency campaigns in place to encourage reduced demands on valuable water resources. The company implemented a temporary use ban (hosepipe ban) for the whole of its supply area, including its Swindon and Oxfordshire supply zone on 23 July 2026 and this remains in place.
There are further demand management actions that are currently under review as part of the company’s drought response, including an application for a Non-Essential Use Ban and actions to encourage increased water efficiency across domestic and non-domestic users.
How long does a permit last?
A permit is intended as a short-term measure to help manage the impacts of drought on public water supplies. It can last for up to six months.
The drought permit Thames Water applied for, to replenish levels in the Farmoor Reservoir would be valid for up to six months. Farmoor reservoir is currently below 70% full, some way below the average for the time of year.
Will the drought permit impact my ability to use my boat on the River Thames?
The Thames catchment continues to experience drought conditions. A return to more significant rainfall is required to replenish water resources in our rivers and groundwater. In response to the pressures on water resources, temporary navigation restrictions are continuing in some locations, including through Oxford, to conserve water resources, maintain navigable water levels, and support essential public water supply abstractions. These restrictions will remain in place until we see a recovery of water resources. The Farmoor drought permit will continue to put pressure on limited resources within the River Thames.