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Thames Water Gives More Detail of Causes of Water Outage Incident

Published on: 2 Dec, 2023
Updated on: 5 Dec, 2023

By Martin Giles

Thames Water has given a more detailed explanation of the problems that caused water supplies to be interrupted for days in Guildford and areas of Waverley borough last month.

But the water company did not respond to a question about the remedial work they have announced in the wake of the incident.

An example of work already scheduled before the water outages suffered in November.

See: Guildford’s Water ‘Island’ To Be Linked Up – CEO ‘Acutely Aware’ of Disruption Caused

Checks of publicly available information show that at least some of the work announced was already necessary because of Notices of Regulation issued by the Drinking Water Inspectorate.

Thames Water (TW) was asked: “Is there any work that has been commissioned as a result of the major incident?” No response to the question has been received.

But TW did explain in more detail the causes of the water outages. A TW spokesperson said: “There were a number of factors that contributed to the supply interruptions. We are undertaking an in-depth analysis to understand the root causes of these interruptions, so the info below may change as we get a more detailed picture.

  • “The power issues affected two of our treatment works. We quickly got these back online, but in the intervening time, the water use by our customers meant that water levels in our service reservoirs (which balance the peaks in demand) had dropped;
  • “Then the heavy rainfall caused a lot of muddy run off and stirred up sediment in the rivers our Shalford water treatment works take water from;
  • “Normally we abstract water into reservoirs and the sediment can settle out before we treat it, however at Shalford the raw water goes straight into the treatment process;
  • “These treatment processes have to work harder when faced with higher levels of ‘turbidity’;
  • “We put the raw water through a multi-stage filtration system and that filtration system was getting clogged up because the raw water was so mucky;
  • “These processes struggled to treat the water to meet the stringent drinking water standards required before we could put water into supply;
  • “As noted above we are investigating why we couldn’t get the water quality to a standard where we could bring the works back on line.”

Nonetheless, it was not explained why a power cut at Shalford water treatment works was given by TW as part of the explanation in some accounts but denied in answers given to The Dragon NEWS, nor why there were no uninterrupted power supply systems, designed to switch in when national grid power fails. They are normally required components of mission-critical systems.

Two public meetings to allow discussion of the incident are being held. One is being organised by Waverley Borough Council on Friday, December 8, and another organised by MPs Angela Richardson (Guildford) and Jeremy Hunt (Surrey South West) a week later.

Public meeting notice

Although it was announced that borough councillors would have to apply for seats as members of the public, a member of Jeremy Hunt’s team said: “An invitation to the Thames Water Public meeting was sent to Tom Horwood by Jeremy Hunt a few days ago. Tim Oliver was invited and will be attending.”

See: Details of MP-organised Public Meeting with Thames Water Announced

Details of the Waverley Borough Council meeting have been given by council leader Paul Follows on Facebook…

Thames Water have said they will not be attending this meeting.

Compensation is another subject expected to be raised at both meetings. During the incident, concerns were expressed that Thames Water had deliberately restored supplies for short periods to avoid whole 12-hour periods without water being reached. Under TW’s compensation scheme, only whole 12-hour periods are counted.

A comment posted under Cllr Follows’ Facebook entry above.

Thames Water launches new tool

Thames Water announced this week its launch of a new interactive map for members of the public to report and pinpoint locations experiencing operational issues across London and the Thames Valley. 

A spokesperson said: “For the first time members of the public will have the ability to view and report potential pollutions, sewer flooding and other issues online. 

“New features have been added such as photo and video uploads to keep users involved in the process.

It is expected that the new reporting tool and interactive map on its website will make it easier and quicker for members of the public to report sewer flooding, blockages or leaks across London and the Thames Valley. The public will be able to report a range of problems online, from either their desktop or on the go via their mobile phone.  

See more related articles here.

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Responses to Thames Water Gives More Detail of Causes of Water Outage Incident

  1. Dave Fielding Reply

    December 3, 2023 at 8:45 pm

    Loved the sub-heading above “Thames Water launches new tool”

    Surely there’s a typo, and the s has been missed off “tool”?

  2. jim allen Reply

    December 5, 2023 at 2:44 pm

    Wow appart from putting me on the A61 not the A3 – it appears Thames Water have got this system working.

  3. Mark Stamp Reply

    December 5, 2023 at 11:15 pm

    Both local MPs Angela Richardson and Jeremy Hunt have been very vocal about the failing of Thames Water on this issue. It is therefore regrettable that neither felt it necessary to speak in the debate in the House of Commons today (Tuesday) on failings of the water industry and whether there should be a stop to executive bonuses in the sector.

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