SES Water’s multi-million pound investment in its Cheam Water Treatment Works upgrade is set to continue in 2026.
SES Water’s multi-million pound investment in its Cheam Water Treatment Works upgrade is set to continue in 2026.

The water company is investing £4.5m to upgrade Cheam Water Treatment Works to ensure the site is more resilient and continues to deliver high-quality drinking water for around 100,000 customers in Sutton, Cheam, Ewell, Belmont, Stoneleigh and parts of Epsom for years to come.
The investment follows an extensive review of the site’s performance after an unplanned shutdown in December 2024 nearly led to all of those customers losing their water supply.
The incident also highlighted that some ageing assets at Cheam needed to be upgraded. The review identified several opportunities for SES Water to strengthen the site’s resilience, and work has been ongoing this year to improve the treatment processes and operational practices.The work is set to continue for another two years.
The company has already carried out a series of upgrades to strengthen the site’s resilience and reduce the risk of supply interruptions for customers, including:
- Improving the site’s water treatment process by replacing equipment in its filtration process.
- Replacing two treated-water pumps and chemical dosing equipment.
- Installing improved monitoring and alert systems.
- Updated emergency planning procedures to strengthen day-to-day resilience.
The upgrades mean the site will be more reliable, issues will be spotted earlier, and there are stronger safeguards in place if equipment fails.
Changes have also been made to SES Water’s emergency planning and response procedures based on customer feedback, ensuring it is better placed to keep customers informed and supported when incidents occur.
SES Water said the improvements have already started to make a difference to the site’s performance and have reduced the likelihood of similar issues occurring in the future.
Planning for the future
The company is continuing to invest in improvements to boost the site’s resilience in 2026, including:
- Replacing key valves
- Refurbishing treated-water pumps
- Installing UV water treatment on site
- Installing new pipework to support the water treatment process.
Together, the upgrades will reduce the likelihood of future disruption and support SES Water’s water quality performance.
Pete Harris, Head of Production at SES Water, said:
“The work we’ve completed at Cheam is making a real difference to the resilience of the site, and the further upgrades we have planned will strengthen it even more.
“We know how important a reliable supply of high-quality drinking water is to our customers, and these improvements mean we are better equipped to prevent issues in the future and respond quickly if they do occur.”
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