I am currently trying to deal with the problem of water bottles falling out of net pockets.

My current solution is to have a small carabiner to clip onto the water bottle. This works in the sense that I don't loose the bottle.

The problem is that I store the backpack in the trunk of the car. Inevitably, BOTH water bottles work their way out of the net pocket. I would prefer to just grab and go when I need to use the backpack. Instead, I have to fish out the bottle out from under something, place them back in the pocket and go. Not as convenient as I would like.

I am thinking about experimenting with a bit of velcro on the mouth of the net pocket. Would sewing on an elastic band around the mouth of the pocket be a better choice?