Thames Water discharged sewage into Slough water for 8 hours overnight on November 29 2025 [from Slough Observer reporter Isabella Harris].
Untreated effluent has been released from the sewage treatment works at Wood Lane in Slough into the Roundmoor Ditch by the Jubilee River. The overnight sewage release started at 9.15pm on November 28 and continued until 5.15am on November 29.
This was not the first sewage discharge of the day in Slough with a further 7.5 hours worth released from 1.15 until 8.45pm on November 28. A week earlier, there had also been a 30-minute release on November 18.
Thames Water have shared a plan for improvements at the treatment works and stated: “Upgrades are planned for Slough STW. These will include an increase in treatment capacity, from 1150 to 1416 litres a second. “This will provide a higher quality of treated effluent going to the river. This scheme will reduce the need for untreated discharges in wet weather. We plan to complete this work in summer 2029. We expect this location to meet all government targets for storm overflows by 2035 – 2040.”
The Roundmoor Ditch travels South from Slough STW via a special type of culvert beneath the Jubilee River and is then the narrow channel seen separating Eton Wick and Dorney Common at the cattle grid. Note the new Dorney Common lake and the Roundmoor Ditch water quality next time you pass that way!
The special culvert is known as an Inverted Siphon: In specific hydraulic engineering scenarios, an inverted siphon is a U-shaped pipe that runs under an obstruction (like a riverbed, valley, or road) and uses gravity and fluid pressure to move a liquid to an outlet point at the same or a lower elevation. While functionally different from a simple culvert, it achieves the goal of crossing beneath a natural watercourse.
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