Although waste and fuel tanks must be vented, it's ok to use an unvented bladder for water.
I followed your Amazon link to check out the tank...it's actually only meant as water supply when dry camping, not for installation on a boat that heels, rocks and rolls. So when you install it, make sure it can't move (hard to do on a sailboat) or it's on a material that can't abrade it. It does come with fittings already installed...that's a plus. However a leaky fitting was one of the complaints, so keep a close eye on 'em and make sure not put any stress on the discharge fitting when you connect the toilet intake line (which will almost certainly require an adapter). I read the reviews-- ALL of which seem to be for only the 60 gal model...they're mixed...durability didn't seem to be one of its best features. I suggest you read 'em--ALL of 'em, 5 star down to 1 star...people were pretty specific about what they like and don't like about it.
Please let us know how you like it after you've had a chance to get "up close and personal" with it long enough to know whether it turned out to be a good buy or not.
Nope, we can't. But you'd be amazed at the number of boat owners who've come to me to save 'em from the results of their not having even a nodding acquaintance with the laws of physics!
--Peggie
