StealYourCarbon is a simple reagent restocker addon. When you visit a vendor who sells an item you have told SYC to buy, it buys it for you. Never run out of water again!
SYC will also attempt to restock from your bank. Note that this feature is fairly simple, if you have multiple stacks of the item in your bank SYC will only pull form the first one it finds. If this stack is not enough to fill your bag the next stack in the bank will not be used until you reopen the bank. SYC will not try to split stacks either, so you'll always get a full stack in your bags if enough items are available on the first stack in your bank.