I'd add to the reasonable sources the companionway boards.
nearly all the water I get in the bilge comes from driving rain coming in through the companionway and either weeping in between the boards, or pouring in faster than the track drains will empty, and therefore over filling and dripping inside.
I hope that the new bimini will eliminate a large ammount of that. I'm actually heading down to the boat this afternoon to look for evidence of new rain leaks following a very heavy downpour yesterday.
We solved this problem by making a Sunbrella cover for the companionway. It is a flat sheet with darts where it makes the turn from the overhead hatch down over the boards. We hemmed the edges and installed a few snaps to keep it in place. Our hatch boards are smoked acrylic (or maybe lexan - were installed by the PO), so the cover has the added advantage of keeping out light in the morning, and giving us some privacy at night. It is also handy to use when there is a light rain as we don't need to keep moving the boards in and out, just secure the canvas cover over the open companionway. Finally, it also protects the teak slides for the hatch boards, which means less frequent varnishing. PM me if you want pics or more details. It is a fairly easy project and is one of the first we tried with our Sailrite sewing machine (prior to moving on to the bimini).