Infinite Water
There are two extremely easy ways to create an infinite water source.
First Method
The first method is by creating a 2x2 hole, as per the image:
And then place 2 blocks of ice or water buckets in opposite corners, as such:
And now you have infinite water that you can take from any corner you choose.
Second Method
The second method is a little bit less popular due to the fact that you can only take water from the center block, otherwise the infinite water source will no longer be infinite. However,
The second method is creating a 1x3 hole, as per the image:
You can then place either 2 water buckets directly or 2 blocks of ice on either end of the hole, as such:
Break the ice, and now take an empty bucket and click the middle water block.