Well, couple ways to check it.
1. Fill the system, let the engine run till it it at tempurature. shut it off and watch for leaks.
2. get a pressure tester (auto zone loans tools) fill the system, pump it up to around 16psi and watch for leaks.
You didnt mention if there is any noises while the engine is running.
The water pump may be on its way out. There is a weep hole in the housing behind the pully, check that as well as hoses. Be careful while working around hot engine fluids, burns really hurt!
Joe