Monksmoor Water Mains Reinforcement Scheme (2026)
A section of the new HPPE water main being installed as part of the Monksmoor reinforcement scheme - Courtesy of @one Alliance
Daventry, a market town and civil parish in West Northamptonshire, England, is undergoing continued development, with significant housing growth planned across the area. As new developments increase demand on the existing water network, additional infrastructure is required to provide capacity for future properties and to maintain the resilience of the wider distribution network. As part of this investment, Anglian Water tasked its @one Alliance to deliver a £1.7m water main reinforcement scheme to support planned growth in the Monksmoor area of Daventry.
Project summary
The project involves installing approximately 1.5km of new 355mm outside diameter high-performance polyethylene (HPPE) water main, together with connections to the existing network. The scheme has been designed around a 50-year planning horizon and has involved detailed hydraulic modelling, route development and consideration of local construction constraints.
The project is nearing completion in late 2026, with the new infrastructure providing additional capacity within the network to support current and planned development.
Anglian Water’s Building for Better initiative scheme board on site – Courtesy of @one Alliance
The issue
The Monksmoor development includes approximately 5,000 new homes planned across the wider area. As more properties connect to the water network, demand will rise, requiring additional capacity to support planned growth in and around Monksmoor, Daventry.
Network monitoring had already identified lower water pressure at a key point in the area. Without additional investment, this could worsen as the number of properties and water demand increase.
The challenge was therefore to provide the required capacity while identifying a practical route for the new infrastructure with as little disruption as possible.
Hydraulic modelling was used to assess the capacity required for new developments and to evaluate the reinforcement’s interaction with the wider Daventry distribution zone. An initial route through a field was explored to minimise disruption to local customers, but investigations found it unviable. The team subsequently developed a route incorporating highway, verge and footway sections.
Further modelling indicated that 548m of the proposed main should increase from 280mm to 355mm in outside diameter to accommodate wider growth, including development around Micklewell Park to the north and Staverton to the south.
A section of the new water main being pulled through and underneath a main road – Courtesy of @one Alliance
Monksmoor Water Mains Reinforcement Scheme: Supply chain – key participants
- Project delivery: @one Alliance
- Principal contractor: Balfour Beatty
- Arboricultural survey: Greenwillows Associates Ltd
- Landowner consultation: Fisher German LLP
- Electrical & plumbing connections: Electrical Design Installations Ltd
- Vacuum excavation: Force One Ltd
- Pipe: Aliaxis UK
- Pipelaying equipment hire: Sunbelt Rentals
- Fittings: AVK UK Ltd
- Fittings: Wolseley UK Ltd
- Fittings: Saint Gobain PAM UK
- Ground investigation & WAC testing: Endeavour Drilling Ltd
- SMR sample testing: Richardson Recycling
- Heras fencing: Altrad Generation UK Ltd
- Reinstatement & muck-away: WN Surfacing Ltd
- Solar tower unit & Daleks CCTV hire: BauWatch (UK) Ltd
- Generator hire: Stuart Group Ltd
- Cabins: Welfare Hire Nationwide Ltd
- Traffic management & traffic lights: Core Highways
- Site cleaning: Scenic Cleaning Service Ltd
- Muckaway grab wagon: Total Aggregates Limited
- MOT Type 1 sub-base granite: Drummond Aggregates Ltd
- PPE, signage, workwear or site equipment: Barhale
The solution
The final solution comprises approximately 1.5 km of new HPPE water main, predominantly installed by open-cut construction. The main section consists of 355mm outside diameter HPPE pipe, with sections installed through verges, highway areas, footways and made ground.
The scope included:
- 340m of 355mm outside diameter HPPE installed in the verge.
- 198m of 355mm HPPE through a Type 2 highway open-cut section.
- 705m of 355mm HPPE through made verge and footway.
- 211m of 280mm HPPE through a Type 2 highway open-cut section.
- Three connections into the existing water network.
- An isolation valve and washout arrangement.
- Associated sluice valves and washouts to support future operation of the network.
The @one Alliance team working together to pull the new water main into position – Courtesy of @one Alliance
The new main connects into the existing network at three locations. Connection A uses an existing service valve and washout arrangement on Admirals Way to connect into the existing 280mm polyethylene main. Connections B and C involve cut-in tees to the existing 12-inch PVC main. These connections include 300mm sluice valves and 80mm washouts, providing the necessary arrangements for isolation and future network operation.
The design was developed using hydraulic modelling to determine the required pipe parameters and to assess the impact of the reinforcement on the wider distribution network. A Modelling Technical Specialist reviewed the water main parameters and confirmed that the proposed arrangement would not adversely affect the required distribution flows.
The reinforcement also supports the ring-main structure of the Daventry distribution zone, enabling it to form part of the wider network rather than being considered solely in relation to the immediate development. The design has been developed in accordance with the Manual of Water Distribution, with hydraulic requirements informed by network modelling.
Soil sampling was undertaken as part of the design process. The results did not identify a requirement for barrier pipe, allowing the specified HPPE solution to be progressed.
The design also provides operational flexibility. Where agreed, future flows can be managed via a three-way arrangement, allowing each leg to be isolated and flushed to a suitable point from the isolated section.
Sections of the HPPE pipe being welded together before installation – Courtesy of @one Alliance
Benefits of the solution
The £1.7m investment provides additional capacity in the Daventry water distribution network, supporting planned residential growth in Monksmoor and the wider area. The reinforcement has also been designed to accommodate wider growth within the Daventry distribution zone, including development around Micklewell Park and Staverton.
Careful route planning and design development enabled the project team to identify a practical alignment for the new main, taking account of local access, existing utilities, vegetation and the surrounding environment. This helped the team develop a solution that could be delivered effectively while considering the needs of local customers and the wider community.
The final route also supports a practical construction approach, with the majority of the new main installed using open-cut methods. The completed infrastructure includes connections, valves and washouts, providing flexibility for future operation and maintenance of the network.
Keeping customers informed
With construction underway along Admirals Way and Eastern Way, customer communication has been integral to the project.
Letters, email updates and targeted social media advertising have kept residents informed about progress, traffic management and what to expect as work continues. The project team is also active in local Facebook community groups, sharing regular updates and responding directly to residents’ questions.
Together, these communications have reached nearly 100,000, helping keep the wider community informed alongside those directly affected by the works.
The newly welded section of pipe being laid into position – Courtesy of @one Alliance
Conclusion
The £1.7m scheme will provide additional network capacity to support Daventry’s continued growth and strengthen resilience across the wider distribution network. Careful planning and collaboration with the local community and supply chain have enabled the @one Alliance to deliver the work while managing disruption.
Sections of the HPPE pipe being welded together before installation - Courtesy of @one Alliance
