Minecraft wiki entry for Trapdoor, associated text: Trapdoors can be moved by pistons. Trapdoors block flowing water and lava. Waterlogged trapdoors release water from all sides apart from the top‌[Bedrock Edition only] or all sides apart from the side that is blocked by the trapdoor itself (and the top)‌[Java Edition only] Lava can create fire in air blocks next to wooden trapdoors as if they were flammable, but the trapdoors do not burn (and cannot be burned by other methods either).