Updated to 1.20
Damn water leaks! We don’t like them in real life, and we don’t want them in Minecraft either.
When there is water above a block, there will be water leaking from it:

To stop it from happening there are a couple of solutions:
- you can use waterproof blocks
- you can use half blocks
- you can put two layers of blocks
So if you want to get rid of those annoying blue dots coming down from your ceiling, you can keep on reading. No need to call the plumber!
Waterproof blocks
To find what blocks are waterproof in Minecraft, we run a little test putting water on top of various kinds of block.

It was very interesting to see that water leaks through blocks like Magma, which would be weird to see in real life, and through blocks like Glowstone and Leaves, which used to leak water in older versions of Minecraft.
Apparently there are only two blocks which the water doesn’t leak through:
- Glass blocks
- Soul Sand
Unfortunately there is not a lot of choice here. If you care about the aesthetics of the ceiling, you will probably not be happy with using only Glass or Soul Sand blocks. If that is the case don’t worry, there are still two more solutions.
Half blocks
As you may well know, in Minecraft there are blocks that only cover half of a block, called Slabs. The idea behind using them is simple: if you put a block that occupies only the bottom half of a block, and put water above it, there will be an “empty” half block between the water and the half block. Let me show you what I mean with this screenshot:

This way the water will not touch the block, resulting in no leaking.
There are many blocks that you can convert into Slabs, like Cobblestone, Sandstone, Granite and many others. You can see how to produce them in How to make Chiseled Stone Brick in 2 different ways, where the production of a Slab is part of the process to obtain a Chiseled Stone Brick.
Two layers
The last option is very simple. If you put another block between water and the block in the ceiling, there will be no leaking. In fact, water leaks only through blocks that it is touching.

As simple as this method is, I kept it last because usually when players are trying to find a solution for water leaks, they are reling on a single layer between the water and the area underneath.
Conclusions
So these are the 3 ways to solve a water leak in Minecraft. Using waterproof blocks could be the quickest way, but it gives you few aesthetic choices. Otherwise you can use two layers of blocks or half blocks. Thank you very much for reading the article till the very end and I hope I’ll see you again around here. See you and take care!