Initial shutdown of Pembury water treatment works leaves customers without water

South East Water's Pembury water treatment works shut down automatically after repeated water quality problems on Saturday 29 and Sunday 30 November 2025, the company said. The treated water was too cloudy for the final disinfection stage to work with certainty, so it did not meet the regulatory standards for consumption, and the works stopped non-compliant water entering the public supply¹. The result was loss of supply or low pressure across parts of Tunbridge Wells and surrounding areas¹. Water returned overnight to the 6,500 affected properties, and the boil water notice that followed was later lifted¹.

The company said the cause was a sudden change in the make-up of the raw water entering the works, which is drawn from springs and wells in the surrounding area. It said this was very unusual and was still being investigated¹. The treatment process was adjusted successfully by Thursday 4 December, after which water from Pembury consistently met all regulatory standards¹. The precautionary boil water notice stayed in place beyond that date so that water produced during the incident could flush through the whole network¹.

From midday on 3 December, customers in the Tunbridge Wells area who had experienced low pressure or no water since 29 November were told to boil water and let it cool before consuming it. The notice covered 24,000 customers². South East Water said the water remained chemically safe and that sampling had detected no bacteria in the area². A map and list of postcodes was published on its website, and affected customers were to receive a letter in the post².

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 deliveries¹. At the height of the incident 36 tankers were deployed¹. Teams made more than 28,000 deliveries of bottled water to around 3,000 customers on the Priority Services Register, and 82,656 litres went to community hubs, Age Concern and the Salvation Army¹. Three bottled water stations were listed on 3 December: Tunbridge Wells Sports Centre, RCP Parking and the Odeon Cinema on Knights Way².

Why it matters for households

Households in the affected postcodes lost supply or saw low pressure from 29 November, and those who had been without water or on low pressure since that date had to boil tap water from midday on 3 December until the notice was lifted². South East Water said the water could be used for washing and flushing toilets throughout, but not for drinking, preparing food or washing dishes without boiling first². The company's supply interruption checklist sets out what households commonly keep to hand, and its guidance on how long restoration can take and on low pressure covers what to expect while a network refills. Its advice on washing without running water applies where supply is cut altogether.

Once the notice was lifted, South East Water advised households to pour away any water they had stored, either onto a garden or into a drain, and to run taps and showers for a few minutes if they had been away or unused, to flush through water left from the notice period. It said this was not needed where taps had been used regularly¹. It advised disposing of ice cubes made with unboiled water since midday on 3 December, changing water filter cartridges, and cleaning machines and replacing filters according to the manufacturer's instructions before use¹. Where water appeared discoloured, it said this came from naturally occurring iron and manganese deposits disturbed by pressure changes, that these are harmless, and that running the cold kitchen tap until clear would allow normal use¹.

What happens next

South East Water said it would carry out a full independent review of what happened and how it responded, and put an action plan in place¹. It said it was planning further improvements at the site by installing more filters to improve resilience¹. It said it had updated all accounts for affected customers, that household customers receive compensation automatically as an account credit, and that business compensation is paid through water retailers, with a separate fund for businesses facing specific financial losses taking the total business package up to £2.5 million¹. It said it was waiving the usual cap limiting compensation to two years' worth of water charges¹.