Poison Water is a purple liquid which is poisoned.
If it goes into Swampy's bathtub, you will fail the level. Swampy will jump out of the tub, and you will have to restart the level. However, it is useful to clear Algae and create small explosions when coming in contact with Toxic Ooze. It is first introduced in level 1-7, Drain it First . Poison is also required to clear the algae on Cranky's food in Cranky's Story. You get Cranky Ducks with Poison Water, but Swampy Ducks and Allie Ducks are killed by it. When normal water touches poison water, the normal water turns into poison water.
- Poison Water does not appear in the chapter Out to Dry.
- Swampy Ducks and Allie Ducks are destroyed and turned into skulls when coming in contact with Poison Water.
- There is an achievement that shares the name of this fluid. To complete that achievement, the player must fill Swampy's bathtub with Poison Water 20 times (The game will track the number of times the player fills Swampy's bathtub until it goes into Swampy's bathtub the 20th time.).