A mechanic has said that my water pump needs to be replaced, but I have had no issues with overheating, leaking, or even the level/temp light coming on.
My car has an automatic transmission.
When a water pump fails, it usually fails by seizing up. It is possible for a water pump to seize up without having any warning lights illuminated. Many times the water pump will make a noise because the bully is no longer able to spend. If you were recommended to replace your water pump do to any of these reasons, I would strongly recommend having your water pump replaced before any further damage occurs.