Sewage in the Lambourn Valley – May 2021 update

Few residents of the Lambourn Valley (or of other nearby places, such as Aldbourne) will be unaware of the sewage problem. This is largely a function of the geology of this beautiful part of the country, in particular the chalk aquifer through which the sewerage pipes run. When the water table is high (generally in the late winter and spring) the pressure on the pipes causes groundwater to rush in through any cracks, so overloading the network.

There are three places where excess foul water can go: off into tankers to be taken elsewhere; out into filtration systems to remove solids and then into the local rivers; or up through drains and toilets into streets and homes. None is ideal but the last is clearly the least acceptable. (This post offers a slightly facetious view of these choices.) It’s for that reason that a steady 24/7 activity of extraction, filtration and removal has recently been a seasonal part of our lives. With every home that’s built, with every new crack in the pipes and with every wet-wipe that’s flushed down a toilet, the worse the problem gets. To some extent, Thames Water is running just to stand still.

The problems in Lambourn were particularly disgusting in 2019-20. In early 2021, they returned but on a lesser level and for a shorter time. Since then, the local flood forums and village groups, the two district councillors, the parish councillors, individuals and media organisations have been pressing Thames Water to address the problem. All agree this is not a simple one to fix. The sewers are old and, by their subterranean nature, hard to examine. Many of the pipes are in private or municipal hands. Changes in groundwater levels do not follow a regular timetable and repairs can only be done when these are at a medium level.

In May 2021, Thames Water effected some sewer-relining work in East Garston and Penny Post was on hand to film the results. You can see the video, which also features comments by local ward members Howard Woollaston and Clive Hooker, by clicking here.

As Thames Water’s Karen Nelson stressed in the video, we all have our role to play in helping with this problem. “Customers can help,”she said, “by only flushing the three Ps – that’s pee, poo and toilet paper. Items like wipes (even if they claim to be flushable), nappies and sanitary products should be binned.” Any problems with flooding, blocked drains or ditches and leaking manholes should also be reported to Thames Water via Facebook, Twitter or TW’s website.

Sewage is something most of us only think about when we have to. Thames Water needs to be thinking about it all the time. Has it been?

In this article in December 2020, we reported on what steps Thames Water was planning to take. On 12 May 2021, we received the statement below saying what had been accomplished and what was planned for the next few months. The real test of what’s been done will come when the groundwater levels start rising later this year. Fingers crossed…

Upper Lambourn

  • In the winter of 2020-21 we installed an above-ground pump at one of our pumping stations where the surface water ditch narrows to help keep the ditch flowing, preventing flooding across the road and into our sewer network.
  • We carried out multiple investigations to identify points of groundwater infiltration in the sewer network and are drawing up plans to resolve the two main areas of concern.


  • We once again deployed the temporary ATAC filtration unit in 2021 but, unlike in 2020, positioned it on the footpath to prevent closing Newbury Road near the fire station. It was in operation from mid-February until late March.
  • Groundwater levels were once again very high in the winter of 2020-21 but the work carried out in the summer and autumn of 2020 to seal and reline the sewer pipes reduced the amount of water entering the network. As a result we didn’t need to deploy tankers to the area as we have in previous years.
  • We have invested £12,000 relining 45 meters of sewer pipes and have more work planned for the High Street in the summer of 2021. This will be around £13,000 of additional investment.


  • There were no problems with groundwater infiltration in 2020-21, despite levels being high. This suggests flooding of the sewerage network in previous years has been from floodwater from the river, not groundwater. As a result we’re checking our network close to the river and making sure things like loose manhole covers that could let water in if the river were to flood in the future, are fixed.

East Garston

  • A £30,000 sewer relining project will begin on 17 May 2021 to line sewers in Front Street and Station Road.
  • We have discovered a manhole chamber on private property which is enabling groundwater or spring water to gush into the sewer network and we’re working with the customer to resolve the problem.
  • We’ve cleaned the whole sewer network in East Garston to make sure it is free of blockages and will continue to clean and monitor the pipes using CCTV throughout the summer and autumn to ensure the network is ready for next winter, should it be a wet one.

Great Shefford

  • Issues stem from surface water entering the sewers in large volumes. We’re in touch with the local authority and the Environment Agency to address this as surface-water management isn’t the responsibility of the local sewage company. As some of the village sewers are connected by pumping stations, the work we complete in Eastbury and East Garston will also help Great Shefford as this will remove some of the excess water which enters the village’s sewers.

The header image (© Thames Water) shows sewer-lining work near Lambourn in April 2021.


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