Wessex Water is introducing additional water sampling in Christchurch Harbour following reports of high E.coli levels and wider pollution concerns.

The company has embarked on a new fact-finding mission with harbour users and is funding weekly water sampling with Hengistbury Head Outdoors, a community-led charity that runs recreational activities in the harbour. It will also trial new water quality monitors to provide more real-time information.

Christchurch Harbour is not designated as an official bathing water, which would require regular monitoring by the Environment Agency. However, it is a popular recreational site downstream of a largely rural area where water quality can be influenced by many factors including wildlife, agricultural run-off, septic tanks, treatment works and storm overflows.

As part of the work, Wessex Water will also sample surface water outfalls that are designed to carry rainwater. This will help identify any properties where wastewater pipes may have been incorrectly connected to the surface water system.

Factors such as rotting seaweed in the harbour, which can often be wrongly mistaken for sewage pollution due to the smell of hydrogen sulphide, will also be assessed.

Matt Wheeldon, Wessex Water’s Sustainable Solutions Director, said:

“We understand how much people care about Christchurch Harbour and why they want clearer information about its water quality so they can continue to enjoy it.

“By working with people who use the harbour and know it best, as well as BCP Council and the Environment Agency, we can build a full picture of what is affecting water quality in all weather and tidal conditions.”

The water company said two high E.coli readings taken by citizen scientists in August 2026 did not appear to relate to Wessex Water’s assets, as there were no storm overflow discharges on or around the sampling dates and all its sewage treatment sites were operating normally.

Environment Agency data does not identify discharges from water industry assets as the reason for the harbour not achieving good ecological status.

While storm overflows discharge mostly rainwater and groundwater to prevent properties from flooding during or after wet weather, Wessex Water is investing more than £8 million every month on schemes to reduce how often they operate in its region. Two overflows upstream of the harbour will be improved by 2030.

The company is investing record amounts in sewage treatment to further safeguard Dorset’s beaches, including a £30 million upgrade of Holdenhurst water recycling centre that was completed last year.

Wessex Water was the first UK company to publish data on storm overflow operations at bathing waters and other recreational areas 365 days a year, with information published every 15 minutes via the Coast and Rivers Watch map.

More recently, it has installed sensors at inland and coastal sites – including Bournemouth and Boscombe Piers – that provide real-time water quality data.

Matt Wheeldon added:

“More widely, we want to see rainwater better managed and returned to the environment close to where it lands rather than entering the sewer system.

“Alongside our ongoing investment, this requires national policymaking that encourages more effective rainwater management at source.”