when used with refined storage, the water from the flask can be put into storage.

It takes 1 bucket worth of water to fill a flask, but the flask contains 5 buckets worth of water.

When you place this water into refined storage, it stores 5 buckets, which can then be removed individually, placed down, and can be used to refill the flask 5 times. Each refill being able to be duplicated again if the steps are repeated.

I believe the flask should be changed from 5000, to 1000, and have each drink from it be reduced proportionally to prevent this duping.

or changed from uses per amount of water stored, to just individual uses available without technically storing the water.

Ok, that makes a lot of sense. Let me take a look and see what I can do. I can't remember why I set it to 5000mb.