A fork of Rural Dictionary
Normally used in reference to bath water. In it's natural environment, bath water is "clean", normally only dirty if your bathtub is dirty itself. But once a body is submerged, often just the lower half of said body, organisms and bacteria transition to the bathwater. Mostly unseen to the human eye, these organisms and bacteria spread throughout the bathwater in the steady metamorphosis into ass water.
If you didn't shower before taking a bath, you might as well have been sitting in ass water.