NORTHUMBRIAN WATER FINANCE PLC

Publication of Supplementary Prospectus

The following supplement to a prospectus (the "Supplement") has been approved by the Financial Conduct Authority and is available for viewing:

Supplement dated 10 October 2025 relating to the £6,000,000,000 Euro Medium Term Note Programme of Northumbrian Water Finance Plc and guaranteed by Northumbrian Water Limited

The Supplement should be read and construed in conjunction with the Base Prospectus dated 6 March 2025 relating to the above programme.

To view the full Supplement, please paste the following URL into the address bar of your browser:

http://www.rns-pdf.londonstockexchange.com/rns/1195D_1-2025-10-13.pdf

A copy of the Supplement has also been submitted to the National Storage Mechanism and will shortly be made available for inspection at:

https://data.fca.org.uk/#/nsm/nationalstoragemechanism.

For further information, please contact:

Alex Rutherford

Group Treasurer

Email: [email protected]

DISCLAIMER - INTENDED ADDRESSEES

Please note that the information contained in the Supplement and the Base Prospectus may be addressed to and/or targeted at persons who are residents of particular countries (specified in the Base Prospectus) only and is not intended for use and should not be relied upon by any person outside these countries and/or to whom the offer contained in the Base Prospectus is not addressed. Prior to relying on the information contained in the Base Prospectus you must ascertain from the Base Prospectus whether or not you are part of the intended addressees of the information contained therein.

Your right to access this service is conditional upon complying with the above requirement. 

Neither this announcement nor the Supplement constitutes an offer of the Notes described in the Base Prospectus for sale in the United States. This is not for distribution in the United States. The Notes have not been, and will not be, registered under the United States Securities Act of 1933, as amended (the "Securities Act") and are subject to U.S. tax law requirements. Subject to certain exceptions, Notes may not be offered, sold or delivered, directly or indirectly, in the United States or to, or for the account or benefit of U.S. persons, as such terms are defined in Regulation S under the Securities Act. There will be no public offering of the Notes in the United States.