In Oxygen Not Included, ice is a water source that is found in Frozen Biomes along with snow and several other resources.
Though it can exponentially decrease the temperature around the colony, ice is a valuable resource once you can melt it into clean water, but that is easier said than done.
In the game, the melting point of ice is -0,65ºC, meaning you would have to increase the temperature around the ice for it to liquefy.
There are a handful of ways to do it, and in this guide, I will name the top three ways I have found to be the easiest and faster ways of melting ice.
1. Melting in Storage
The first method I found could be the easiest for beginners, but it is far from being the most efficient.
This method requires mining the ice and, akin to any other minable resource, mining it destroys half of its original mass, meaning a loss of a great deal of much-needed water. Even so, it is a good method to use in emergencies.
First, you will need to build a Storage Bin. Set its element filter to accept only liquefiable materials.
To speed up the process, I like to set the priority high, so the workers sweep the ice into the storage bins before they continue with any other tasks.
Lastly, wait. Soon the ice will melt and, using the Mop option, the Duplicants can mop the clean water off the floor and place them in bottles around the storage area or use it for whatever machinery or building requires it.
This, however, is not dependable over time, particularly when living in a cold environment. If left unattended, the water will freeze again and the Duplicants will put it back in storage.
I advise you to keep a close eye on what is happening and be ready to order the workers to mop with high priority.
TIP! When in the Manage Duplicant Priorities menu, click the cog in the upper right corner to open the options and click “Enable Proximity“. This will make the workers prioritize tasks by how distant they are to the task.
2. Using Machines
While obvious, using heat to melt the ice is not as straightforward as building a heater next to it. Space Heaters, while useful, are not strong enough for the ice.
On the other hand, more cost-efficient builds draw more heat than Space Heaters. Building a couple of batteries, or even a coal generator, is a more cost-efficient and faster way to achieve our goal.
As an alternative, I chose to set up an Electric Grill next to the ice I found. While my Duplicant was cooking, the heat from the grill melted the ice next to the grill.
It is not the most effective way to melt ice and get clean water, but it is more efficient than spending time on research to build a heater, and it feeds your colony.
3. The Ice-E Fan
This is the most difficult and time-consuming way of melting ice, but it works quite well. It takes a couple of cycles to reach the Temperature Modulation upgrade under the Gases research option but, if it is not an emergency, I find it easy although slower than the options above.
This method might not be the best if your colony is living in a cold environment since the Ice-E Fan cools the temperature of the room and does not work in temperatures below 10ºC. (If the room contains Hydrogen, the Ice-E Fan will work in lower temperatures.)
With that being said, the Ice-E Fan uses ice to cool the room, melting the ice and dropping a bottle of water.
What I found to be the best option was to place your Ice-E Fan next to machinery that produces heat. (i.e.: The Printing Pod, any Generator, any battery, any Research Table or Workbench and others.) The heat of the building is displayed when hovering over the item.
In my personal experience, the storage method has saved my colony on multiple occasions but, eventually, taking advantage of the heat produced by your machines would prove to be a more efficient way to melt ice into water.
Even so, the most amusing method I found is placing a grill next to the ice. Efficient and hilarious!