The water bags come with substantial corner grommets that we attached 1/4" eye bolts to, but they come with no fill nor draw fittings. You purchase them separately and decide where they go to suit your needs. Not a problem with a hard plastic tank: you basically just drill holes and use thruhull fittings. The water bladder uses the same concept, you just have to cut two perfect circles in the bag and hope it works, which it did perfectly, but it makes you nervous.
We put one of the tanks inside the keel. This used to be a 70 gallon fiberglass water tank (the hull sides and a top), but we choose not to trust our sole source of drinking water to 43 year old Chinese polyester with keel bolts inside. This tank is the reason we are switching to the Nauta bags in the first place.
When it fills up, it wedges in the keel quite nicely, and since this is an old water tank itself, it is isolated from the bilge by bulkheads and a top.
The other tank went in the bottom of the galley pantry locker, located under the pineapple. The faucet is also new as the old one stuck up above the companionway. Not only did it obstruct the entry, but it's absurd height made it's water stream more of a splashing spray. Not very efficient. The deep pantry well has been a conundrum for a while. We had considered the amount of food that could be stored there, but the method of retrieval seemed excessive, especially when we've got so much storage elsewhere. The water tank fills the space perfectly, and even still we raised the shelf another six inches to be able to reach the pots and pans inside and give the tank full bulging capability.
AJ made a nifty little selector manifold for the tanks that feeds to a fine screen filter to protect the pump. Why did we never get around to painting this compartment? I don't know. The third feed nipple is hopeful. We have a space set aside on the starboard side, just no third tank yet.
So far it's all been working great!