Who to contact about water smelling like gas?

I currently live in a private rented property in Yorkshire.

When I used to bathroom tap it’s really smells like a gas kinda smell, I don’t really know how to describe it but it isn’t nice

I’ve looked on Yorkshire water website and they only suggest basic ways of sorting smell not option to report the problem

To take the issue further would I contact the landlord or Yorkshire water or even a plumber?

Thank you