Phil, I am guessing that you AC condensation pans are rusted out and they are leaking. A AC unit has two sets of pans that catch and send this condensation out via Pvc pipe to the exterior of the home. The first pan is the primary pan, and the second pan is the secondary or last chance pan. When the first pan rusts out, the second pan kicks in. When this goes out, the thing leaks.
you can go into the attic with a light and examine the situation. you need to look directly under the unit. You could even have algea clogged lines. how often do you pour bleach into the pans for algea clean out? I recommend once a month during AC times.
If your AC is not in the attic, then all I have said is of no revelance.
But its a start.
Come back with more details and we can pinpoint the problem for you.