Committee publication · Correspondence · 13 January 2026
Correspondence from Chris Train, Chair of South East Water regarding the hearing on the Tunbridge Wells water outages on 6 January, dated 12 January 2026
From: Environment, Food and Rural Affairs Committee
Inquiry: Reforming the water sector
Summary
South East Water's Chair Chris Train responds to the EFRA Committee's questions about divergences in evidence given during the 6 January hearing on Tunbridge Wells water outages. Train defends the company's position on foreseeability, details the technical causes (raw water chemistry changes affecting coagulation), describes an independent review led by a non-executive director due by April 2026, and addresses DWI concerns about jar testing frequency, staffing levels, and out-of-hours monitoring.
Key findings
- SEW commissioned an independent rapid review by Caroline Sheridan (non-executive director) with three workstreams (Technical, Customer/Communications, Incident Management), to be completed by April 2026 with all findings shared with the Committee.
- The incident was caused by an unprecedented combination of raw water chemistry changes (turbidity, alkalinity, pH, temperature) that pushed the existing coagulant outside its operational range; only one other water company (Thames Water) had experienced a similar issue.
- SEW missed a scheduled quarterly jar test in October 2025 due to process scientist sick leave, but Train argues this had no causal link to the November–December event.
- The company argues continuous staffing at Pembury WTW would not have made the event foreseeable or avoidable; 24-hour operational control room monitoring turbidity performance via SCADA and duty scientist rotas were maintained throughout.
- Microfiltration unit installation accelerated to 15 December (normally 6–12 months) but requires booster pressure rectification; expected operational by 13 February 2026.
Tone
ProceduralTopics
Key actors
Chris Train, South East Water, Environment, Food and Rural Affairs Committee, Drinking Water Inspectorate, Caroline Sheridan, Ofwat, Thames Water, Southern Water
Notable line
“… the precise nature of the event was not foreseeable for reasons I explain briefly below. Coagulation SEW has used the particular coagulation chemical at Pembury WTW for the last 20 years.”
Key Quotes
“On behalf of the entire Board of SEW, I offer our sincerest apologies for this.”
“These impacted the coagulation process, in a manner that has not been seen before. In this set of circumstances …”
“The fact that SEW has not previously experienced this very complex combination of circumstances and there is limited precedent among the convened industry expert group is what led us to the conclusion that this event was not foreseeable in advance.”
“… at all times scientists were available to monitor the issues at the WTW and to provide operational support.”
“Ofwat's decisions to, among other things, refuse to fully fund key resilience schemes meant that, as a board, we were left with no option but to take the difficult decision to appeal Ofwat's PR24 determination to the Competition and Markets Authority ( CMA ) in March”
Source · parliament.uk record ↗