Definition
An infinite water source is an endless supply of water that is either created naturally or by the player. Whenever you use a bucket to scoop water out of this source, it will just fill right back up again and again, thus meaning it is an infinite water source. These are not difficult to make usually, but in certain spawning biomes (where the player spawns when opening a new world) it is more difficult to obtain. This infinite water source is the easiest to make for all biomes except tundra biomes.
Warm Biome Infinite Water Source Creation
Creating one in a warmer biome is simple. First, find any water source naturally generated by the world, and fill an empty bucket up with water. Next, go to a place near your base and dig out a 2x2x1 hole. Fill it with water and then go back to the water source you previously came from. If that water source is gone, search for a different one. On the second fill, dump it on the side with lower elevation. On the third one, fill it in the middle, so that all blocks are equally filled with water. This creates an infinite water source, not so hard is it? Well, you'll learn that it is a little bit more complicated in tundra biomes.
Tundra Biome Infinite Water Source Creation
Same rules apply to creating an infinite water source in this biome than others, but with a few added steps. You need to have at least one ring of torches around your hole where the water will be located. If you don't, the water will freeze, and will turn into useless ice. If you break the ice, it will freeze over again. Since torches can melt snow, it keeps the water at a safe temperature that other biomes naturally offer. Same goes for farmland in these biomes. Surround the entire crop with at least one ring of torches. This should keep you water at a safe temperature, thus will keep crops as fertile crops.