Say which fixture it is, how long it has been doing it, and whether water is going where it should. A dripping tap, a cistern that keeps running, and a mixer that is loose on the bench are different jobs.
Isolation
Many fixtures have a small isolation valve underneath. If it turns without force, you can stop one tap without shutting the house down. Do not force a seized valve.
In a unit, a leak can affect the property below. Tell the owner or the managing agent as well as the plumber.
The quote
Ask whether the price is a service call plus parts, and which parts are included. A washer, a cartridge and a whole mixer are not the same replacement.
Get a quote
PlumberQuotes introduces you to a local plumber. It is not a plumbing contractor, and it does not promise a time.