Federica Quimia, a sixteenth century Spanish witch, experimented this potion on herself. We have her final recipe, but don't have the process of how she created it.

Lethe River Water

A myth was that those who died, drank from the river so that they could forget their lives before dying. This river came from the Kaybetti River. The Kaybetti River is a small river from Turkey, near Oren. Lethe River water is a strong memory suppressant. Magical people & Muggles can be vulnerable to this river. In smaller doses, it can cause loss of memory. In high doses, it can cause body systems to not work due to forgetfulness. It can cause comas or even death. Lethe River water is like normal water molecules. There is no difference between magical water & mundane water. Lethe River water does not have fungi or bacteria; it is the cleanest water on earth. One theory is that a very strong magical person enchanted the river for unknown purposes. Another theory suggests that there is a magical fungi or plant in the river's source. There could be magical properties that are carried through the river from the source. No one has yet to reach the source.

Fun Facts
⊱ Federica found a similar but powerful potion than today's version, which effects only mild forgetfulness.
⊱ Lethe River water is named from the Muggle Greek & it is one out of five Underworld rivers.
⊱ The Kaybetti River was enchanted from over a thousand years ago.
⊱ An enchantment could have been restructuring particles in the Lethe River water's source.