Do you know that you are not supposed to reuse disposable plastic cups?

All plastic containers are problematic. It’s not just plastic cups. Reusing water bottles is another source of issues. Chemical leaching, bacterial growth, etc. are all issues. I’ve even heard there is a chance of microplastics getting into the liquids you put into these containers if they are reused.

My recollection is that it depends on the type of plastic that the cup is made of.

Polypropylene = OK
Styrofoam (polystyrene) = NO

https://plasticoceans.org/7-types-of-plastic/

I have two pop/soda/coke bottles I keep water in for drinking in my truck. Have used them for several years. I suppose it’s the same as drinking out of a plastic military canteen…

I think only items made of PET (#1) cannot be reused. Most plastics can be HAND washed and reused. Dishwasher cleaning seems to encourage some type of undesirable leaching.