Creepy Liquid

Creepy Liquid is a liquid Material that expands infinitely unless contained in a completely closed off area. It can be turned into water with Purifying Powder.

Creepy Liquid is identical to Water in most respects, except for the fact it's purple and it glows. Additionally, bathing in creepy liquid will not remove stains, unlike water. As long as you have the Breathless perk, you will be safe from its effects. Creepy Liquid will irreversibly choke and drown the world unless you are extremely careful.

Trivia

 * Creepy Liquid is likely a reference to the Creeper World games, where you fight against the spread of a substance called the Creeper with similar function and color.