Right my answer to this is .......

empty your bottle .... weigh 2kgs of water fill your bottle should come to less than half way .... so
make sure your dip tube finishes half way so if your bottle is sat at an angle you should not draw
liquid and if your flipped upside down the liquid should not come over the end of the tube so in effect
with a tube in you should never draw liquid ......

I MIGHT BE WRONG ...... but thats what i work on ....