I don't know if this will help, but it has worked wonders for me. I buy bottled water in 8 oz bottles. Then I am able to drink the bottled water, and the 8 oz stays cold. I also freeze the bottles and then let them thaw slowly in the fridge so that the water always stays cold. They are the perfect size for 1/2 package of crystal lite on the go too. I hope this helps you as much as this helped me. Good luck!
Peace and love,