I found a really neat idea online for cup washing in public restrooms, and its less bulky than a water bottle to carry around, especially if you don't use a purse!
Its called "WuduMate".
It was really invented for Muslims, who are using public restroom. "Wudu" is their washing ritual (hey pray 5 times per day, and they must rinse their intimate areas, face, hands, forearms and feet with water 3 times before each prayer). It allows them to wash the intimate areas in a public stall. And hey, I also know a few muslim sisters who use a menstrual cup, so that could be extra useful for them!
Anyway, it is basically a plastic water bag with a spout and handle, which can be folded up and put in your pocket, or your purse, then re-filled and emptied, and folded back up again for next time!
I thought it might be a really cool way to manage cup washing in a public wash room too, you could just fill it up at the sink before you go in. Or even for people who just had a baby, to help keep clean "down there". Or out doors while camping! Here is a link to it below with pictures, I would say see if you can find some websites where you can order one-- try it out! I plan to get one soon. And it if turns out to be really useful, I might ask them if they need any American stockists :D:
What do you think?