I've tried using a zip lock bag to recharge my cooling vest. They didn't last very long. I had a light weight roll top bag laying around that the vest fit in. Now I just add water and roll it down the required three rolls and clip it shut. No leaks or spills. When I'm ready to wear it I dump out any remaining water and put it on. Roll the empty bag up and clip it onto one of the Rok strap that hold my gear on the back seat.
I hadn’t considered that… thanks for the tip!