If you find a leak, you have to drain the affected area and re-do it. You will just test with tap water anyway right? Once you have done the test, drain the system entirely and make sure to get ALL of the water out down to dry components.
DOn't forget that the plumbing itslef will require a certain volume of water, so be prepared to add more when you fire up the system. Mark any leaks, drain and fix. Then re-test.
Good Luck!!
