Network Access Code and WSSLs

Retail competition was introduced in December 2005, through the Water Supply Licensing (WSL) regime (for water only). From 1st April 2017 the WSL regime was replaced by the new Water Supply and Sewerage Licensing (WSSL) regime.

 This allows new entrants to compete and provide certain water services. There are two types of WSSL:

1. A WSSL with retail authorisations allows a retailer to purchase water and sewerage services from an existing Water Company such as Severn Trent at wholesale prices and sell on to eligible customers. Read about our wholesale charges.

2. A WSSL with wholesale authorisations allows a third party to sell water from its own source to an eligible customer, using the supply system of an existing company (Severn Trent).  A link to our Indicative Combined Access Prices can be found at the bottom of this page.

To facilitate the WSSL process, two key documents have been created in accordance with the Water Act 2003 and in compliance with Ofwat’s guidance:


From 1st April 2017 all non-household customers are eligible to choose which licensed retail company supplies their water services. Eligibility guidance is published by Ofwat and more information on the new market can be found on the Open Water website.

New Appointments and Variations - NAVs (also referred to as Insets)

Visit our NAV page to see details of services available to NAVs.

For further information on competition in water, please contact:

Wholesale Market Unit
Severn Trent Centre
2 St John’s Street,

Email:  (for inset / NAV enquiries only)

Document downloads

Want to know more about competition in water? Get in touch.

Wholesale Market Unit, Severn Trent Centre, 2 St John’s Street, Coventry CV1 2LZ.