Leaking Avent bottle driving me mad. Why is it happening?

[CitrusZest]

I sterlise all 6 bottles my daughter uses each day in one go so all the teats and necks get mixed up. There is generally one bottle a day that leaks and no matter what I do I can't make it stop. I'm being driven mad!
What could be causing it? I've tried slackening it, tightening it and throwing it against a brick wall!
Heeeeeeelllllpppppp!

I found they usually leak when the lid is not on properly, sort of cross threaded? or the teat is not quite in place.
Nothing else for it but to check each bottle for leaks each time you fill it.

do you scrub the outside of the thread of the bottle, and the inside of the thread of the neck?

Try loosening it to the point of another thread, and the re-tightening. Also, don't tighten as much as you can, that will make it worse.

agree with not over-tightening it - ours tend to leak if dh has done them as he tightens them more than me.