cditch, I had water coming in this weekend as my rear bilge kept turning on every now and then. Looking in bilge in rear, I found water running from front to back on other side of the stringer. Went forward and under deck, opened up the hatch and found that the 3 way connector for the sinks was loose and spraying water. When I lifted up the fitting, the hose actually pulled off without any effort. Seems that clamp was never installed far enough back on the fitting. Reinstalled and problem gone. But, all my Water in the fresh water tank was now gone...tank empty. So when I returned home, refilled and no more leaks.
Check for loose fittings and also if your water tank empties faster than normal, might be possible that is your leak.