If you're going to be away from home for an extended period of six months, it is generally recommended to leave the dishwasher door open. The reason for this is to allow the interior of the dishwasher to dry out completely, which helps prevent the growth of mold and mildew.
When the dishwasher door is closed for an extended period without use, moisture can accumulate inside the appliance, creating a favorable environment for mold and mildew to thrive. By leaving the door open, you promote air circulation, allowing the moisture to evaporate and reducing the risk of mold growth.
Additionally, you may want to consider turning off the water supply to the dishwasher to prevent any potential leaks while you are away. This is an extra precaution to avoid any water-related issues during your absence.
So, the best practice is to leave the dishwasher door open and turn off the water supply if you'll be away from home for an extended period like six months.