A potion of water is, as one would expect, water. The Guidebook states that every clear potion is a potion of water. Thus water is the one type of potion that you can identify by appearance. (No one expects water to be red or smoky.)
Identifying any clear potion will provide Discoveries knowledge (accessed by \) that all clear potions are potions of water. Once discovered, a blessed clear potion is listed as a potion of holy water, while a cursed clear potion is listed as a potion of unholy water. Using an altar to determine beatitude of future potions of water will identify all potions of water as holy, uncursed or unholy appropriately.
Dipping into water
If you dip an object into an uncursed potion of water, it will become wet. (Metal objects rust, potions of acid explode, scrolls become blank...) This is almost useless, because you can just dip into a different source of water such as a fountain or pool. It is far more useful to change uncursed water into blessed or cursed water.
Dipping an object into blessed or cursed water does not make the object wet. In brief, holy water will uncurse cursed objects or bless uncursed objects, while unholy water will debless blessed objects or curse uncursed objects; then the potion is used up and disappears (or you have one less potion of water in your stack). The beautitude of dipped object becomes known. You can dip an entire stack of objects each time.
Dipping blessed object into blessed water, or cursing object into cursed water, produces no effect.
Obtaining uncursed water
- just find one, or buy one at shop
- dip any potion except water or acid (once for a diluted potion, twice for a non-diluted one) into a fountain or a moat (for the latter, you need water walking or polymorph to a monster which can fly)
- enter a moat with any potion except acid or water in your inventory (without wearing oilskin cloak; dangerous unless you have magic breathing; all objects not in oilskin bag become wet).
- cancel any potions except fruit juice, sickness, see invisible, booze and oil.
- dip a unicorn horn into a Potion of confusion, a Potion of blindness, or a Potion of hallucination to turn the potion into a potion of water.
- sometimes it may be useful to dip holy water into unholy water, or vice versa. You can dip a whole stack of them. This uncurses all the dipped potions, and uses up one potion into which you dipped them.
If you quaff uncursed water, you get 1d10 nutrition points ("This tastes like water.")