Yes. WaterSafe will accept NVQ Level 2 as a minimum, accompanied by a Water Regulations Certificate, but recommends S/NVQ Level 3, to be fully competent.
Take a look at the 48 list of accepted qualifications and reference entry routes - when your work will be assessed for competency.
Experienced plumbers can also opt to take the BPEC Experienced Worker qualification which is suitable for plumbers with at least five years' experience in the trade. You'll first need download and complete the initial assessment form to ensure you are eligible for the qualification.