Is this a portable water dispenser that you purchase bottles of water and place on top of the dispenser?
OR
Is this water dispenser permanently connected: hard wired not plugged in and connect to your plumbing (cold water connection)?
Portable: Contact the company that supplied the water dispenser. It likely requires a thorough cleaning.
Permanently connected: Again, contact the company that supplied the water dispenser. It likely requires a thorough cleaning. You may also be required to hire both an electrician and a plumber.
Whom i should consult ? An electrician or a plumber ??