Jimm 4/25/2013The simplest test to perform would be a cooling system pressure test. You can do this test yourself, with the engine cold - by using a pressure tester kit - available usually for free or for a small fee (like a deposit) from any local auto parts store; Advance Auto, Auto Zone, NAPA - and the like.
Be sure to test the cooling system with the engine and system cold - and just be sure not to exceed the pressure rating as labled on the radiator or cooling reservoir cap; such as '15 psi'.
The cooling system pressure test will apply a pressure to the static cooling system and any leaks can then be identified - whether at the water pump or not. This test will save considerable cost by helping to identify if there is any leak and where it orignates from.