Put in a ziplock bag or container right after use and keep in the fridge (dont have to be freezer) till next use. Thats what i do when i pump at work, wash and sterilise only after i reach home.
You can put the pump parts in a Ziploc bag and store it in the fridge. The cold pump parts won't cause your breastmilk supply to drop.
Wash and sterilize after each use for hygiene purpose Store at chiller only when you really no time to wash
It's disgusting if don't wash after use
Sterilize aft every use
Wash after each use