How do you clean a urine drainage bag? can it be washed?

the bag's packaging says single use only, does that mean I can't wash it? i heard you can wash urine bags out with soap water, rinse it out, and hang it to air dry. if i don't wash it will the urine inside get contaminated? the bag was exposed to air when i changed it out so it's no longer sterile. but if i do wash it, it's not gonna be sterile anyway. the bag is connected to an indwelling catheter inside the bladder.