The Drinking Water Inspectorate (DWI) announced on 4 December 2025 that it has begun a full water quality investigation into an event affecting water supplies in the Pembury and Tunbridge Wells area, where South East Water has served a boil water notice to consumers1. The DWI is the quality regulator for public water supplies in England and Wales1.
The investigation will cover the company's actions in the lead up to, during and after the event, and will include a review of the company's communications with consumers to protect public health1. The Inspectorate said it is gathering information to support an event assessment, which will include a complete evaluation of the contributing risks, and that it cannot provide further details while the investigation is live1. It has powers to bring forward enforcement action or legal proceedings should there be sufficient evidence1.
The DWI set out how such cases are handled. Water companies are responsible for the treatment and distribution of drinking water and, where failures occur, must decide on the appropriate action to protect the health of consumers and comply with the relevant legislation1. During an event the Inspectorate investigates the actions taken by companies where required, assessing whether they accord with The Water Supply (Water Quality) Regulations 20161. The Inspectorate investigates all drinking water quality events in England and Wales and will take enforcement action where there is sufficient evidence that an offence was committed, where the company does not have a defence that it took all reasonable steps and exercised all due diligence, and where prosecution is regarded as being in the public interest1.
"Consumers should follow the advice provided by South East Water if they are within the affected area and should contact South East Water if they require further information."
The DWI added that anyone still concerned about water quality should direct those concerns to the company in the first instance1. The notice carries an update dated 18 December 20251. The number of properties affected, the duration of the boil water notice and the cause of the loss of supply have not been reported in the DWI notice.
Why it matters for households
Households in the Pembury and Tunbridge Wells area who are within the affected zone are subject to a boil water notice served by South East Water, and the regulator directs them to follow the company's advice and to contact the company for further information or with remaining concerns about water quality1. The investigation examines both the company's operational actions and how it communicated with consumers during the event1. The DWI has not published a timetable for the investigation or said when its assessment will conclude1.
Households elsewhere can use our guides to prepare for a supply interruption, including what to do if you get a boil water notice, a boil notice checklist for your home, how to check if there is an outage in your area, how your water company will contact you in an incident and how water companies respond to a major incident. Practical preparation is covered in our supply interruption checklist, guidance on how much drinking water to store per person, a home drinking supply storage checklist and where bottled water stations are set up. The water hub collects these guides.
What happens next
The DWI says it is gathering information to support its event assessment and cannot provide further details while the investigation is live1. It has the power to take enforcement action or bring legal proceedings if there is sufficient evidence1. No date has been given for the conclusion of the investigation or for any decision on enforcement1.
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