Minecraft wiki entry for Translucency, associated text: Water cauldrons, despite containing water, render this water as completely opaque. While it was rendered translucent as expected in prior versions, this seems to be inconsistent and possibly hardware-dependent, and when it fully stopped is currently unknown. Its opacity is also a parity issue, as cauldron water appears translucent as expected in Bedrock Edition. This persists to the present day.[1]