Barrels need to be cleaned with Steam or Water before using them again.
Mods introducing new content into the game.
Augmented or new ways of transporting materials - belts, inserters, pipes!
Since you clean them with water, it seems like unbarrelling water shouldn't create dirty barrels?
Hmm, that is true, I'll see what I can do.
The mod has been updated with your suggestion, Plain water barrels no longer need cleaning when emptied :)
