£6M Water Infrastructure Project Launched in St Helens 2026

Key Points

• United Utilities has completed a £6 million underground stormwater storage tank in St Helens, Merseyside, capable of holding 700,000 litres of water.
• The tank is designed to reduce the number of times the storm overflow operates at Carr Mill, thereby improving water quality in Black Brook.
• Since installation, the tank has already prevented five discharges into the local watercourse, according to United Utilities.
• This project is part of a combined £10 million investment on two storm tank schemes in St Helens as part of the Big North West Upgrade.
• The second storm tank, located at Gaskell Street, targets spills into Sutton Brook and is being built alongside restoration of a local kickabout football pitch.
• Work in the area included tree removal, surveys, trial holes and associated environmental mitigation, with tree replanting and grass seeding planned for spring–summer 2026.
• The site is expected to be fully reopened to the public from early July 2026, once fencing is removed and landscaping completed.
• Gemma Vidamour, Capital Delivery Manager at United Utilities, said the tanks are already making a measurable difference to the environment.
• The initiative reinforces United Utilities’ commitment and investment in Merseyside’s future water infrastructure and long-term environmental goals.

St Helens (Liverpool standard) July 02, 2026 – The new underground stormwater storage tank installed by United Utilities in uk/local/st-helens/">St Helens, Merseyside, is designed to capture excess rainwater during heavy rainfall periods and temporarily hold it underground rather than allowing it to flow directly into the local watercourse.

As reported by United Utilities in its corporate newsroom, the company has installed an underground stormwater storage tank capable of holding 700,000 litres of water “in periods of heavy rainfall” which will help reduce the number of times that the storm overflow operates at Carr Mill. This reduction in storm overflow operation is intended to improve the water quality in Black Brook, a key local waterway affected by historic discharge events.

In operational terms, the tank acts as a buffer between the surface-water drainage system and the natural watercourse. When rainfall exceeds the capacity of the downstream system, excess water is diverted into the tank instead of being spilled over through the storm overflow. Once the rainfall subsides and downstream capacity increases, the stored water can be gradually released or processed, minimising sudden pulses of polluted stormwater entering Black Brook.

Capacity and performance so far

The tank’s capacity of 700,000 litres is significant in the context of urban stormwater management in St Helens. As noted by United Utilities, this volume is sufficient to absorb a substantial portion of storm runoff from nearby roads, housing areas and public spaces during typical heavy rainfall events.

According to the company, since its installation, the tank has already stopped five discharges into the local watercourse, highlighting the project’s early success. Each of these prevented discharges represents a separate event where stormwater, potentially carrying pollutants such as oil, sediment and debris from urban surfaces, would otherwise have been released into Black Brook via the storm overflow.

Gemma Vidamour, Capital Delivery Manager at United Utilities, stated: “We’re pleased to see the storm tanks are already making a difference to the environment by holding excess stormwater, and improving water quality in the nearby Black Brook.” This direct quote underscores the measurable environmental benefit already observed in the first months of operation.

How does this project fit into the wider £10 million investment in St Helens?

The £6 million Carr Mill tank is not a standalone initiative but one element of a combined £10 million investment on two storm tank projects in St Helens, Merseyside. As described by United Utilities, the two projects are located at Hawes Avenue (where the Carr Mill tank sits) and Gaskell Street, and are intended to increase stormwater capacity and improve river water quality across the town.

The Hawes Avenue project, which includes the newly completed underground tank, is specifically aimed at reducing the frequency of storm overflow operation at Carr Mill and improving water quality in Black Brook. This aligns with the broader objective of the Big North West Upgrade, a regional programme designed to make the North West “stronger, greener and healthier” through improved water infrastructure.

The second project at Gaskell Street involves the construction of another underground stormwater storage tank to reduce spills into Sutton Brook. This parallel scheme mirrors the design and purpose of the Carr Mill tank but targets a different watercourse in the St Helens area, demonstrating a coordinated approach to stormwater management across multiple local rivers.

Integration with local land use and community spaces

Both projects have required temporary disruption to local land, including tree removal and the occupation of parts of public spaces. As reported by United Utilities, teams continue to work with St Helens Council to re-plant 13 trees in the local area after six were removed to carry out the work at Hawes Avenue.

At the Gaskell Street site, United Utilities is working with St Helens Council to reinstate a kickabout football pitch on the site, with work expected to be completed in summer 2026. This dual focus on environmental improvement and community amenity restoration is a defining feature of the wider investment plan, ensuring that infrastructure upgrades do not permanently degrade local recreational spaces.

Grass seeding at the Hawes Avenue site is scheduled for the end of May, with fencing to be removed and the site reopened for public enjoyment from early July 2026. These timelines reflect a carefully managed approach to environmental reinstatement and community access, balancing engineering needs with public use of the area.

What environmental and community benefits are expected from the new tank?

Water quality improvements in Black Brook

The primary environmental benefit of the new underground stormwater tank in St Helens is the improvement of water quality in Black Brook. Historically, storm overflows at Carr Mill have discharged diluted wastewater and surface runoff into the brook during heavy rain, introducing pollutants and increasing nutrient loads that can harm aquatic life.

By reducing the number of times the storm overflow operates, the tank directly limits the volume of polluted water entering the brook. As noted by United Utilities, five discharges have already been prevented since installation, which is a clear early indicator of the tank’s effectiveness. Over time, repeated reduction in overflow events should lead to measurable improvements in water clarity, oxygen levels and biodiversity in Black Brook.

Local environmental restoration and public access

In addition to water quality gains, the project includes environmental restoration measures such as tree replanting and grass seeding. United Utilities has committed to re-planting 13 trees in the local area after six were removed to facilitate construction at Hawes Avenue. This replanting effort is designed to mitigate the visual and ecological impact of the work and to maintain or enhance the local tree canopy.

The site is scheduled to be reopened to the public from early July 2026, once fencing is removed and landscaping is completed. This ensures that the infrastructure upgrade does not result in long-term loss of accessible green space for residents. As Gemma Vidamour explained, “It highlights our commitment and investment in Merseyside’s future, and we look forward to working with the local authority on future schemes.”

Background: The development of stormwater infrastructure in St Helens

The underground stormwater storage tank at Carr Mill is part of a broader, multi-year effort by United Utilities to address storm overflow issues across the North West. The project stems from the Big North West Upgrade, a regional programme that targets improved water infrastructure, reduced environmental discharges and enhanced resilience to heavier rainfall patterns linked to climate change.

In St Helens specifically, the company has identified two key waterways—Black Brook and Sutton Brook—as priorities for intervention due to historic storm overflow activity. The decision to construct two separate underground tanks, one at Hawes Avenue and one at Gaskell Street, reflects a targeted approach that combines engineering capacity increases with local environmental and community considerations.

The £10 million combined investment builds on earlier work in the area, including surveys, trial holes and temporary tree removal, which were necessary to assess ground conditions and design the underground tanks appropriately. This phased approach demonstrates a commitment to detailed planning and environmental mitigation, rather than a purely rapid construction model.

Prediction: How this development can affect residents and local water users in St Helens

For households and local communities

The new underground stormwater tank is likely to have several indirect benefits for residents in St Helens. By reducing the frequency of storm overflows, the project helps to lower the risk of surface-water pollution entering local streams and drainage systems, which can, in turn, reduce the likelihood of localized flooding and odour issues associated with overflow events.

Over time, improved water quality in Black Brook could enhance the aesthetic and recreational value of nearby green spaces, potentially increasing footfall for walking, leisure and community events. The planned reinstatement of trees and grass, along with the reopening of the site to the public, supports this aim by ensuring that infrastructure improvements do not come at the cost of long-term loss of accessible space.

For environmental groups and water users

For local environmental groups, anglers, and organisations involved in river conservation, the tank represents a tangible step towards reducing the impact of urban stormwater on natural watercourses. The prevention of five discharges already suggests that the tank is functioning as intended, and if similar reductions are achieved at the Gaskell Street site, the cumulative effect on Sutton Brook and Black Brook could be significant.

In the longer term, if the two-storm-tank model is replicated in other parts of Merseyside, St Helens could serve as a reference case for how underground stormwater infrastructure can be integrated with community amenity restoration and environmental mitigation. This could influence future planning decisions by local authorities and water companies across the region, potentially accelerating similar projects in other towns with comparable storm overflow challenges.