Thorpe Malsor sewer fix reduces spill risk

Anglian Water and North Northamptonshire Council have completed a joint drainage scheme in Thorpe Malsor after investigations found historic road gullies were sending rainwater into the village’s foul sewer network.

The partnership has invested more than £1 million to improve drainage capacity and reduce the risk of pollution during heavy rainfall. The work followed environmental spills in the North Northamptonshire village, where extra surface water was placing pressure on pipes designed to carry wastewater.

Since April 2025, the historic connections had contributed to more than 30 spills in Thorpe Malsor. The scheme is intended to reduce that pressure, protect the local environment and lower the chance of flooding affecting residents.

Historic road gullies found in foul sewers

Anglian Water technicians identified a number of older highways road gullies connected into the foul sewer network. Road gullies collect rainwater runoff from streets and are normally linked to surface water drainage systems, not wastewater pipes.

Further checks by Anglian Water’s specialist Misconnections Team and Complex Investigation and Resolution team found 15 historic connections from highways gullies into the foul sewer.

The connections were described as having been installed appropriately at the time. Over the years, changes in the local area meant the additional rainfall entering the foul network was putting too much pressure on local wastewater treatment processes.

During heavy rain, that extra water could increase flows through the sewer system and raise the risk of overflows into the environment. If left unresolved, the same pressure could also have increased the risk of flooding for homes and land nearby.

New surface water route for rain runoff

North Northamptonshire Council’s Highways Team delivered the physical works after Anglian Water worked with local stakeholders to investigate the issue and agree a longer-term fix.

The historic highway connections were removed from the foul sewer network. New road gullies, along with the village trough commonly known as a natural spring, were redirected into a new surface water drain.

That change separates rainwater runoff from wastewater, helping the foul sewer operate closer to its intended capacity during periods of heavy rainfall.

Reduced pressure during heavy rainfall

The practical effect for Thorpe Malsor is a drainage system better able to cope when intense rain falls over a short period. Surface water from roads and streets should now be directed away through infrastructure intended for rainwater rather than adding volume to wastewater pipes.

For residents, the change matters because overloaded foul sewers can increase the risk of sewer flooding and environmental spills. For the local landscape, it reduces the likelihood of pollution reaching nearby watercourses and habitats during storms.

Anglian Water said the work also supports resilience against climate change, with flash downpours becoming more common. Drainage networks built or adapted for older rainfall patterns can come under stress when short, intense storms add large volumes of surface water quickly.

£1 million partnership linked to wider upgrades

The Thorpe Malsor scheme forms part of Anglian Water’s wider programme of infrastructure investment. The company has described its current business plan as its largest, worth £11 billion, with upgrades aimed at improving performance for customers and building resilience against climate impacts.

In this case, the issue was not a single broken pipe but a set of legacy drainage arrangements that no longer suited the way the village and its wastewater network now operate.

The joint work between Anglian Water and North Northamptonshire Council shows how older connections can remain hidden until investigations trace the source of repeated spills. In Thorpe Malsor, those checks led to the removal of the historic gully links and the creation of a dedicated surface water route.

Source: North Northamptonshire Council

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This article is based on the published North Northamptonshire Council notice and checks the reported figures against the source details.

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• Confirmed the affected place as Thorpe Malsor in North Northamptonshire.
• Checked the reported investment figure of more than £1 million.
• Checked the number of historic gully connections reported as 15.
• Checked the source claim that more than 30 spills had occurred since April 2025.

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Source

North Northamptonshire Council

Scope

Thorpe Malsor

Updated

2026-06-11 14:42

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Article contextPeople & topics#7

#Anglian Water#North Northamptonshire Council#pollution prevention#road gullies#surface water drainage#Thorpe Malsor#wastewater network

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