South East Water restarted the Pembury Water Treatment Works on Wednesday 3 December 2025 with an instruction to boil the water before drinking, preparing food or washing dishes, after repeated water quality problems at the works on Saturday 29 and Sunday 30 November1. The company says the boil water notice for Tunbridge Wells and surrounding areas has since been lifted with immediate effect, and that water returned overnight to the 6,500 affected properties1.
The company said the water produced at Pembury was too cloudy (turbid) for the final disinfection process to have worked with absolute certainty, so it did not meet the strict regulatory standards for consumption, and its systems shut down the treatment process automatically1. It said the make-up of the raw water changed suddenly for reasons it is continuing to investigate, describing this as very unusual, and that the treatment process was adjusted successfully by Thursday 4 December1. While the notice was in place the water was chemically safe, and sampling showed no bacteria detected in the area, the company said1.
"The problem was caused by repeated water quality challenges at our water treatment works in Pembury on Saturday 29 and Sunday 30 November."
Support during the incident included more than 37 million litres of water tankered into the network since Friday 28 November and more than 1.9 million litres of bottled water handed out through bottled water stations and deliveries to customers on the Priority Services Register1. At the height of the incident 36 tankers were deployed, teams made more than 28,000 deliveries of bottled water to around 3,000 customers on the register, and 82,656 litres were delivered to community hubs, Age Concern and the Salvation Army1.
| Item | Figure reported by South East Water1 |
|---|---|
| Properties affected | 6,500 |
| Water tankered into the network since 28 November | More than 37 million litres |
| Bottled water handed out | More than 1.9 million litres |
| Tankers at the height of the incident | 36 |
| Bottled water deliveries to Priority Services Register customers | More than 28,000, to around 3,000 customers |
| Water delivered to community hubs and charities | 82,656 litres |
The company said the notice stayed in place after 4 December as a precaution, to make sure all water produced during that time had flushed through the entire network, with sampling from source to tap against Drinking Water Inspectorate standards1. It said it is waiving the usual cap on compensation, that household customers will receive compensation automatically as an account credit, and that the total package of compensation to businesses is up to £2.5 million1.
Why it matters for households
The notice covered parts of Tunbridge Wells and surrounding areas; the company published a map and a full list of postcodes1. With the notice lifted, the company says tap water no longer needs boiling and is safe to drink and use as normal1. Its guidance for households afterwards includes pouring away any water stored during the incident, onto a garden or into a drain, and draining and refilling storage tanks1. It advises running taps and showers for a few minutes if they have not been used, because water from the period of the notice may remain in the pipes, and says this is not needed where taps and showers have been used regularly1. It also advises disposing of ice cubes made with unboiled water since the notice was issued at midday on Wednesday 3 December 2025, changing water filters, and cleaning drinks machines and replacing filters according to the manufacturer's instructions before use again1. Where water appears discoloured, it says this is caused by naturally occurring iron and manganese deposits disturbed by pressure changes, that these are harmless, and that running the cold kitchen tap until clear is sufficient before normal use1. It asks customers to tell neighbours that the water is safe again1. The site's guide to boil water notices and boil notice checklist set out household steps for this kind of incident, and its water in an emergency guide covers wider supply disruption.
What happens next
The company says it is planning further improvements by installing more filters to improve the resilience of the site, and will carry out a full independent review of what happened and how it responded, with an action plan for improvements1. It says it has updated all accounts for affected customers, who should have received notification by email or post, and that payments to water retailers for business customers are being fast-tracked, with a separate fund for businesses that faced specific financial losses to be managed independently, with details of how to apply to follow1. The company's page also carries a separate update about a later supply issue in Tunbridge Wells caused by recent pipe bursts, which it says is not related to the boil water notice and does not affect the safety of the water in the system1.
Sources (1)
- Boil water notice for customers in Tunbridge Wells | South East Water, southeastwater.co.uk
Boil Water Notice Advice
Boil Notice Checklist
Water in an Emergency
Do Not Drink Notices
