Anyone get this problem with MAM bottles

[Gigi10]

So I make the formula up usual way. I usually run the bottle under cold water in the kitchen sink to cool it down....but I've noticed that the tap water somehow seeps into the bottle- I think through the anti colic vent holes at the bottom? Does this happen to anyone else and how do I stop it?! Very frustrating...I end up chucking the formula and starting again and then just waiting a lifetime for it to cool enough

I had this problem when I tried these bottles (they didn’t work for my DD though) but I read somewhere you’re supposed to loosen the top (with the teat) or take it off so there isn’t a vacuum.

I used to hold them upside down, so water falls on top of the bottle if it was too hot.it didn’t then go near the bottom area. That was quite a few years ago now though and I imagine they are less leaky too

I think it's to do with a vacuum effect with the hot and cold water. I rarely needed to do this as I used a perfect prep machine.