I was building the water elevators using soul sand and magma blocks diagonal to each other. Let's say I put the magma block and soul sand at height 10, then I put signs to the right, in the front, and to the left of the blocks at height 11 and 12 so i can fit in and expecting the water not to go through the signs. You can place a water bucket on whichever block first at height 11 and it'll not move. You can do that for 12, too, and above if you continue above the same block. However, if you try to put down water on the opposite block, a new water source will form in the place of the sign with the sign still there and it'll flow like normal water being blocked by nothing. Since I like to make small builds in tight spaces, an elevator that is right next to each other is needed and the diagonal adds aesthetics. It doesn't concern me much about my aesthetics as much as it concerns me that some really cool builds might not work because of this, and the rather inconsistency of the signs blocking water. In the images you can see how on the soul sand water is placed 2 blocks high, but once water is on the magma block, it goes everywhere. I followed it up by stopping the sources i put down on the soul sand and magma block to show that new sources actually appeared where the signs are, which is visible in the last image.