To keep the mod as realistic as possible, we should either make finite liquid or use the finite liquid mod. Water doesn't multiply normally, so water should be one of the main things you will need to transport to your colonies. Water should be used up in the growing of crops hydroponically and because it is used for fuel, there needs to be a limit to it in space. Also, it would work as an ok coolant for engines. Water would also be used up that way. The finite liquid mod would be a good choice because it also includes air tanks that you can wear and have limited air. This would be one less thing to program. It also has a feature where if you put either lava or fire near iron blocks, it gets red hot and evaporates water. If this was shared with other metals, it would be realistic for overheating engines and would use coolants.