Analysis reveals sewage spill that lasted more than a year

New analysis by the Liberal Democrat party has revealed a previously unknown prolonged sewage leak that lasted for an entire year.

The analysis, based on recently released DEFRA data shows that multiple spills of sewage into British waterways have lasted for hundreds of days at a time.

The data showed South West Water oversaw the longest lasting sewage leak. In one instance, South West Water oversaw a singular spill lasting for the equivalent of 366 days, meaning leaks occured every day across the period.

The spill predominantly affected the Salcombe Regis Stream, a coastal waterway just east of Sidmouth in Devon. The company has said they are investigating the cause of high spill numbers from the Salcombe Regis site, positing that several “unauthorised connections to the sewer network are contributing high levels of additional flows into the sewer.”

A leak overseen by Southern Water was the second longest in duration, the analysis shows. On one occasion in their region, sewage leaked into the River Lavant for an equivalent of 285 days – with 287 spills recorded. The Lavant flows directly into Chichester Harbour which is a site of special scientific interest.

A recent study showed that chemical pollution at the Lavant site increases over 100 times after spillages.

The company, which covers Kent, Hampshire, Sussex and the Isle of Wight, also appears multiple times in the list, placing at sixth place with a spillage of 228 days recorded into a tributary of the River Test.

Wessex Water and Anglian Water also saw long lasting leaks. Their longest spills saw waste pumped into rivers for 269 days and 229 days respectively.

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The 269 day leak, recorded at Hurdcott wastewater treatment works, overseen Wessex Water, was from a high groundwater site, where groundwater enters the sewerage network and causes overflows to automatically operate to prevent flooding. Wessex Water noted that these discharges are not among the reasons for the River Bourne not achieving good ecological status.

Anglian Water admitted they “know our customers will be disappointed to see an increase in our storm overflow data this year”, and pointed to extreme weather and persistent flooding as reasons for the longer spills.

A spokesperson said: “We know our assets need to be resilient to changing weather patterns. We also understand the strength of feeling around storm spills, and having apologised, we have promised transformational action – because we know our climate is going to keep changing, so we have to find better ways of dealing with extreme rainfall.

“Our next five-year business plan builds at pace on the work we’ve already started. It contains our largest ever investment  – £1bn – into tackling storm spills, and £11bn overall to improve our performance. We’ve prioritised this work to deliver the biggest benefits first, because we recognise and share the desire of customers to get on with addressing this issue.”

A 217 day spill into Quinny Brook in Shropshire was documented by Severn Trent, the UK’s second largest water company.

A Severn Trent spokesperson said: “We’ve recently completed improvements at our Church Stretton site – including relining of pipes to prevent ground- and river-water from entering the system, adding storm water storage and increasing treatment capacity – which is having a positive impact on spills reduction.  

“In Shropshire, we’re investing more than £250million to improve storm overflows and over the last 12 months and we’ve already installed around 150 solutions along the River Severn with more to come. We expect that by December 2025 we will have reduced spills to the Severn to an average of 18 per year.  

“We’re committed to making a lasting difference and to play our part in helping Shropshire’s waterways be cleaner for generations to come.” 

The managing director of wastewater services at South West Water said in a statement: “We are one of only five companies in the industry to reduce spills compared to 2023. Our focus has been to reduce spills at beaches in the bathing season by 20 per cent in the last five years as we continue to focus on what our customers care about. We have also been focused on the highest spilling sites from 2023 and have already removed three-quarters of the top 20 sites.

“This is part of our 15-year investment plan – and while change on this scale takes time, we are already seeing positive results.

“We’re also proud to be an industry leader on data and transparency. We measure more spills, more often and therefore have highly accurate data.

“This progress has been made despite 2023/24 being the wettest hydrological year on record, with exceptional rainfall and groundwater. Against this challenging backdrop, the reduction in spills shows our plan is working – this is not an excuse but is important context.

“There is more to do and we are moving in the right direction driven by our determination to deliver on our customers’ priorities.”