If there is a whole in the middle of the cover of a bottle,how many milimeter maximum the whole may be not to create a problem of mayim megulim thank you..
Most people are not careful not to drink any water milk, wine etc. that was uncovered nowadays, however if you want to be makpid you can. I haven’t seen anyone that writes anything regarding a whole in the cover, but the hole should not be large enough that a snake can get inside. What diameter snake, I don’t know.