bait well

[oldfielder]

My i/o has that in-deck baitwell right about where fellowship has his but I've never gotten up the nerve to plumb it. I sure would like to, but that big drain hole in the bottom of the transom scares me a little. Does the line have a check valve in it? Does it have a shut-off to manually seal the line?
I've often thought that I should just put a portable on deck, as I don't do too much live bait, but that's surrendering even more deck space than thei/o already takes up.