Holy water is a Ranged weapon that is used just like throwing knives and darts; however, it is only effective against demons. Holy water is non-tradeable and has a +6 Ranged attack bonus when wielded. It is very effective against most types of demons when used.
The making of Holy water is learned during the Legends' Quest. It cannot be made by players who have not made sufficient progress into the quest. A blessed gold bowl, blessed by Gujuo, can be used to transfer the pure sparkling clear water found within the Kharazi pool into enchanted vials to make Holy water. Once the water is gathered into the bowl via a reed cut from the tall reed plants by the pool with a machete, it will need to be poured into enchanted vials which, when filled, are stackable. One bowl will fill 10 enchanted vials. It is also possible to enchant the vials and siphon the sparkling water directly from the pool into the vials, but this is slower, since only one vial is filled per reed.
The most effective way to make Holy water in bulk is to make 27 or 28 if dropping 1 bowl while filling the others blessed gold bowls (takes a while), fill them, and use Karamja gloves 3 to teleport to Shilo Village. It is important to note that if you try to leave the jungle on foot, the water will disappear from your bowls.