With every new Genshin Impact update, we get new characters and weapons in the game, and to ascend them, we need to farm their ascension materials. One of them is the Drop of Tainted Water which is an ascension material required to ascend Lyney's signature weapon, The First Great Magic and it will become available in Genshin Impact 4.0 update to farm.
As per the leaked in-game description, Drop of Tainted Water is "A small drop of water obtained from the Tainted Hydro Phantasm you defeated. The life force in it has yet to ebb away." Since Fontaine will be the new region coming with the update, you will be able to find Drop of Tainted Water in it; however, it will be a difficult task to explore a massive region to farm them, and thus, here are their exact locations to save you a lot of time.
Genshin Impact: Drop of Tainted Water Farming Location
Drop of Tainted Water can be found only in Fontaine, and to farm it, you will have to kill Tainted Hydro Phantasm as per Honey Impact. These are strange elemental life forms that have appeared in the waters and you will find two types of Tainted Hydro Phantasm in Fontaine, including Water Splitting and Water Spounting Phantasm.
Since the Fontaine region is not out yet, there is no information about Tainted Hydro Phantasm's locations in Genshin Impact, and there are no leaks around this as well. We will update this page once Genshin Impact 4.0 update releases and Tainted Hydro Phantasm gets available in the game, so make sure to keep an eye on it.
You will need a total of 23 Drop of Tainted Water to ascend The First Great Magic to its highest level. You can travel fast from one location to another by using Teleport Waypoints and the Statue of Seven to collect them quickly. In addition to this, make sure that your HP is enough to fight enemies, as you might encounter some while exploring.