Hi all I’m from a design background and I have a number of questions in relation to water flow within a container (e.g. coke bottle and larger). I punch a few small holes in the base of the (PET) coke bottle and then I fill it up with water, once I have done that, I place the cap back on the bottle. The water within the bottle has stopped dripping from the base, and when the cap is opened, the water flows through the holes of the base. What forces are doing this? Is it the airtight seal that has repreasuriezed the container? Or is it hole size 2mm. Alternatively, perhaps it’s something else like material selection or the design profile of the container? This method works fine for some containers (HDPE and PET) 2 litres up to 5 litres. So now, I’ve scaled up the project to a five-gallon HDPE container. It has failed to act in the same way as the other containers. Why?