A good place to fill vials with water (after you've started the Recipe for Disaster quest) is right in the Lumbridge basement. You can fetch the empty vials from the Culinaromancer's chest and fill them at the nearby sink.
Suppose you can buy the vials for 11 each. If you only need 60 seconds to buy a fill inventory and take it to the bank, and you only need 90 seconds to take a full inventory from the chest to the sink, fill them, and go back, then it takes about 150 seconds per 28 vials, which we'll round to 6 seconds per vial. In one hour, you can get (3600/6) 600 vials bought and filled. 600 x 80 is 48,000, which is about how much you make per hour filling vials with water.
Needless to say, there are many better ways to make gold.
Swamp Toads (about 250,000 per hour) and Swamp Tar (about 175,000 per hour) are two good ways to make gold without any skills, combat levels, or quests. Search here or on the internet for guides on how to do those.
