Southern Water has pleaded guilty to two charges relating to environmental permit breaches after polluting the River Test, a vital chalk stream in Hampshire. The admission came at Medway Magistrates Court on 14 July 2026, following an investigation by the Environment Agency into a significant pollution incident that occurred in March 2023.
The Environment Agency initiated its investigation after routine water quality checks on 13 March 2023 revealed dark particles in the River Test near Stockbridge. Tracing the pollution upstream, investigators located the source almost four miles away at Southern Water’s Fullerton wastewater treatment works. The discharge was found to contain suspended solids at more than three times the permitted limit and significantly elevated levels of iron, which gave the plume a distinctive red tinge.
Evidence presented by the Environment Agency indicated that only one of the four tanks designed to remove sludge and scum at the Fullerton site was operational at the time of the incident, with one tank awaiting repair for over a year. Furthermore, pumps responsible for filtering finer contaminants were also experiencing problems. The company's own site diary confirmed these technical issues had been logged days before the pollution was detected.
A critical aspect of the charges against Southern Water was its failure to alert the Environment Agency about the issue, or the failing equipment, when it became aware. The company later acknowledged that its internal procedures for raising concerns about effluent quality and notifying the Environment Agency had not been followed before or on the day of the incident.
Chalk streams like the River Test are designated as precious natural resources, known for their unique ecosystems and clarity. The pollution posed a particular threat to the river's genetically distinct salmon population, which requires clean, well-oxygenated water to thrive. Simon Moody of the Environment Agency emphasised that Southern Water's safeguards had failed, leading to an unacceptable compromise of the river's health.
The Environment Agency has been actively monitoring water companies, hitting its target of 10,000 asset inspections this year. This included over 730 checks at Southern Water sites, with 68% found to be compliant with their permits. Following these inspections, officers issued Southern Water with more than 400 improvement actions. Southern Water will face sentencing for these breaches at a later date, with two additional charges expected to be taken into consideration.