Cabin sole water damage CD27

[freitknecht]

Just some follow-up and questions. Finally I got to spend some time on the boat and figured a lot out. I didn't find any water actively leaking onto the cabin sole, but there was water at the bottom of the port settee. This led me to open the holding tank, which I found completely full. This is very strange, since of course we all know the tank should have been pumped out; and not only that, the previous owner had a "no use" policy with his head for at least a few years in passing. There IS a macerator and a y valve, but overboard discharge was never allowed nor practiced where he sailed. I emptied and rinsed the tank a few times, and came back a day later to find some water (a bit less than previously) still present in the original spot (there was a small amount of water still in the bottom of the tank that couldn't be completely pumped out). Here's the question: would there be some way for water to get into or back up into the holding tank over time if there was some dysfunction in the system? Remember, though, that the amount of the leak was minimal over multiple four seasons. Ideas?