[kijin]

You are limited by how much liquid your digestive system can absorb in any given hour. I've heard that it's somewhere around 1 liter per hour. Any excess liquid is going to slosh around in your intestines instead of entering your bloodstream.

Meanwhile, your liver can remove about 10g/12ml of alcohol per hour. In order for you to reach a meaningful BAC, you will need to absorb significantly more than that.

For example, drinking 1 liter of 1% alcohol solution per hour will not result in any significant BAC, because you can remove alcohol from your bloodstream faster than alcohol enters your bloodstream. You've got a well-optimized queue there.

5 liters of 1% alcohol is the same as above, just repeated 5 times. Your queue is still working fine.

1 liter of 5% alcohol, on the other hand, will dump 50ml of alcohol into your bloodstream within an hour. Now you have a backlog, and this backlog is what increases your BAC.

So dilution does matter, even if the absolute amount of alcohol is the same. You're basically diluting alcohol consumption over time.