Check all the water pipes, also be sure to check the plastic ones that go into the block, they also have a tendency to break with age. The radiator might also be leaking. The easiest way would be to look where the water is actually coming from. Also check that the bleed screws are all properly fastened.
Also check the oil, if its milky it might be head gasket problem.
Just be sure to properly bleed the cooling system once you have fixed the problem.