I just wash mine in the machine with vinegar, sometimes with baking soda. Don't do vinegar
and baking soda though. Hello volcano science project
Oh and hot water = smelly, it will really stink out your house.
Occasionally I do use a bit of bleach when they're really dirty and don't clean well after one cycle. Then I put them in the dryer and leave them for weeks before I use them again (I have about 4 in rotation).