It depends on the problem. If it's leaking, but not too bad, just keep and eye on your coolant level. If the pump is not working at all, you should not drive it. If the coolant level gets too low the vehicle may overheat.
〉 Answered on Feb 22nd, 2007 by Lori Johnson, Owner and Instructor at Ladies Start Your Engines
I would heed our expert's advice but here is some more information on how to know if you need to change it (remember this is just a suggestion and to know for sure, make sure you have a technician check it out or change it):
How to Tell if Your Car's Water Pump Needs Replacements.
Difficulty: Moderately Easy
water pump is the device that pumps the coolant through the cooling
system. It is driven by a belt and operates only when the engine is
running. Water pumps fail with some regularity - you can expect to
replace yours sometime before 100,000 miles, if not sooner.
Turn the engine off and open the hood.
Locate the water pump pulley. The pulley is the round part that the
belt is attached to. To find it, look for the belts. You will see more
than one pulley. Your car will have an alternator with a pulley and
perhaps an air conditioner, power steering and smog pump pulleys. If
you are unsure, ask your mechanic to point out the water pump pulley.
Grab opposite ends of the round pulley and check for "play"
(looseness): Try to rock it back and forth. There should be no give. If
there is, the bearings are going and it's time to replace the water
pump. By the time you can feel play in the water pump pulley, you may
also be able to hear the bad bearing when the engine is running - there
may be a low-pitched grinding noise coming from the water pump pulley.
Visually check the water pump (it's located behind the pulley) for
signs of a coolant leak. If the water pump gasket is leaking, it must
be replaced. This is a good time to get a new water pump, too, unless
it was just recently replaced.
Tips & Warnings
water pumps are driven by the timing belt, which is under a plastic
cover. If this is the case with your car, you cannot easily diagnose a
bad water pump bearing yourself.
pumps usually fail in one of two ways: either the bearing for the
pulley goes, or the gasket (or seal) behind the water pump begins to