In biomes with air, a full tank begins as a vibrant blue and gradually turns red as it heats up. When it is completely red the train will then catch fire. Fire spreads to nearby wagons, making them cease functioning until the fire is put out. To keep the tank wagon cool, players must fill the water bucket with water, and approach either the tank wagon itself or the train engine. Tank is also cooled down by rain.
In biomes without air, the water tank instead provides oxygen in a large radius.
A tank wagon can be upgraded twice in Endless game mode. If players upgrade this wagon, the next iteration will yield a higher capacity water tank making it so that it doesn't need to be cooled as often, as well as increasing the radius of oxygen around it.
|Capacity||Time||Space Radius||Bolt Cost|
|LVL 4 ()||400%||120s||7.8||-|
|LVL 5 (2x )||500%||150s||9.4||-|