Let's take a look at how to make infinite water in Minecraft. All you're going to need is a shovel, and you're going to need to make a hole that's two by two. And I messed this up, so make sure I fill that in. You need three buckets of water. Drop one in each corner, and the fourth corner will fill itself up. You can see now it's a source block. So now you can just refill your buckets, and all your source blocks are still there. Now, with potions this is good because a cauldron which is good for filling up water bottles can actually only hold enough water for three bottles. This has unlimited water. You can fill it up as many times as you want. Also good to have it in your mine shaft or whatever in case you encounter lava and need some water and a bunch of other stuff. You used to be able to do this with lava, but it doesn't work anymore. There's no way to make infinite lava in Minecraft. Sorry.