Sewage Action Group for the Lambourn Upper Valley – November Report

The SAGLUV Team were recently invited to a progress review meeting with Thames Water’s Simon Brittain, Head of Thames Valley Waste Operations.

In short, it was a most encouraging update.

At our previous meeting with TW’s Regional Operations Team at the end of October, it was confirmed that all of the relining, repair, and sealing work that had been planned had now been completed, including 500m of relining in Weston that was urgently needed.

However, the purpose of this meeting was to update SAGLUV on TW’s more strategic view of how they plan to address the remaining sewerage issues of our part of the Lambourn Valley, and the wider catchment. Here are the key points:

Additional investment for resolving cases of internal sewer flooding in people’s properties

Over the next 5 years significant investment is planned to reduce response time by more than half. Current response time averages c11 hours, and the additional investment will reduce this to an average of 4 hours for more than 90% of the time.

To achieve this objective, TW are increasing their fleet with an additional 50 fully crewed, specialist vehicles, i.e. tankers, jetters etc.

This type of flooding generally occurs in the winter months, and further benefit from this investment will be gained during the summer, when the crewed vehicles will be used pro-actively for increased planned maintenance and sewer cleaning.

Catchment sewer lining

Some excellent news here: Whereas, to date, TW’s approach has been to identify groundwater infiltration leaks and reline that section to stop the leak. Then to wait for the next period of high groundwater, identify more leaks to repeat the exercise, and so on….

TW are now planning to carry out a pro-active programme of relining during 2026 to cover the stretches of pipework that have not already been relined in the recent and past programmes, whether ingress has been identified or not. This is a major step forward that will result in virtually all TW’s pipework in our area being relined.

The appointment of a specialist infiltration engineer is further evidence that TW is determined to crack the problem of groundwater infiltration which is the root of our problems.

Pumping Stations and Rising Mains

We previously reported that the rising main (main sewer pipe) that runs from Eastbury to East Garston is going to be replaced. That in itself is great news.

However, it may be even better than that. TW are currently investigating whether a pipeline can be laid from Eastbury Pumping Station to the rising main that runs from Lambourn to the Treatment Works. If this can be achieved, the rising main running from Eastbury to East Garston will be redundant, thereby reducing the volume of sewage in the system serving East Garston and Great Shefford. We eagerly await news on that development, but even if it is not possible, the current pipe will still be replaced anyway.

East Shefford Sewage Treatment Works

The results from the recent £14m upgrade of the ES STW continue to be very encouraging as TW are developing their understanding of the newly installed Actiflow plant, which is a ‘first of its kind’ application for wastewater treatment.

The results we quoted in our last report were taken in the winter when the plant was dealing with sewage that was hugely diluted with groundwater. The results below were recorded during the summer months when there was virtually no dilution, providing a much sterner test of the plant’s capabilities. This table shows the EA Permit limits with the actual levels recorded which are very positive:

	Suspended Solids	Biochemical Oxygen Demand	Ammonia	Total Phosphorous	Iron
Permit Limits	25 mg/l	15 mg/l	3 mg/l	0.25 mg/l	4 mg/l
Results 31 May 2025 to 29 October 2025	4.7 mg/l	2.0 mg/l	0.29 mg/l	0.1 mg/l	1.358 mg/l

The sewer work that has been completed, the further work that has been planned, and the STW upgrade, all lead us to believe that our objective of Clear Sewers and a Clean River, can actually be achieved.

Another serious point that Simon wanted to share with us was the issue of sewer blockages, and we feel it is important that this should be widely publicised. The following is an extract from the report that TW produced for us.

Facts and figures on blockages / wet wipes

Why do we need a ban on wet wipes containing plastics?

Environmental and consumer impact:

• Blockages made up of wet wipes are the leading cause of pollution incidents in the Thames Water region.

• 12.5% of all pollutions in 2024 were caused by paper/rag, with wet wipes the main component.

• Across 2024 and 2025 so far, 19.5% of all blockage-caused internal sewer floodings were caused by paper/rag blockages.

What Thames Water is doing:

• We remove an estimated 3.8 billion wet wipes from our network every year.

• We clear 75,000 blockages annually, costing £40.7m – a £200m cost for customers over the current five-year investment cycle (2025-2030).

• In partnership with the PLA (Port of London Authority) we worked to remove 5 million wet wipes from Wet Wipe Island in the River Thames in Hammersmith - equivalent to 12 double-decker buses.

• We cleared a 100-tonne - equivalent to 8 double-decker buses - wet wipe blockage in October 2025 from a sewer in Feltham, West London; taking over a month and requiring specialist teams equipped with gas monitors.

The message is clear! If you have to use them, don’t put them down the loo! We have responsibilities too.

And don’t be fooled by those marked “Flushable”. It’s true they will vanish from sight, but they don’t break down and the blocking effect is the same.

A further meeting with TW’s Operations Team will be held in the New Year, and another strategic level session is planned for the spring.

Thames Water are certainly demonstrating a continued commitment to working with SAGLUV, for which we are extremely grateful.

SAGLUV Team

November 2025