Brining this thread back up.
On my 2006 X2, there is one water intake on the bottom for the ballast. It then goes through a hose, to a check valve, and then to the distribution manifold.
All 3 pumps draw from the distribution manifold, and when the tanks are full they overflow through each vent hole for each tank.
When you drain the tanks, the pumps pull water from each tank back to the distribution manifold. The distribution manifold has its own 2 drain lines (1 on each side back of the boat) that allows all 3 tanks to drains their water from.
So for winterization, you either have to suck in RTV antifreee into the manifold, or disconnect the line at the check valve to drain the water, otherwise the water will be stuck inside.
Am I correct?