Minecraft wiki entry for Desert_well, associated text: Desert wells generate in desert biomes. They have a 1⁄1000‌[JE only] or 1⁄500‌[BE only] chance to be generated in any desert chunk. It is possible for a well to generate around a cactus. The well is considered a natural feature rather than a structure, and therefore it generates with the "Generate Structures" option disabled.[1]