All kinds of things will grow on the water pipes, drains and containers. That's normal. I can take all of them out super easy on our old siemens washing machine, we're talking less then 15 minutes. Rinse, put them in a dishwasher, put back in 15. that smell is gone for a couple of years. Good luck doing this on a more recent washing machine. I wouldn't recommend leaving the door open. Some rubber parts don't like it if they are dry for too long.