Bests & Worsts Reviews from Amazon

For some reason this pink one does not keep my water cold. I have the same bottle in black which I love. Now I put them both on my counter put 5 ice cubes in both. And then filled them with cold water from my brita pitcher so they are both identical. Fast forward six hours, the pink one is room temperature and the ice is gone. The black one still had the ice left. Sixteen hours and the black one still had ice, eighteen hours and it was still cold. Are the colored ones made different? The reason I bought another was because I was so happy with the black one.