In many cases, the water supplier will simply need a description, diagram and plan of the work, the contact details of who is authorising it and the plumber’s name and address if an approved plumber is being used. More details can be found on the WRAS website.
If you use a WaterSafe approved plumber, they are able to carry out some types of work without notification. This is because they have specific training in the strict regulations required to install pipes and fittings to supply drinking water.
Getting permission is quick and free, but failure to notify your water supplier could result in extra costs to put poor plumbing right or, worse, contamination of water supplies and a court prosecution.