> a normal mug of ~500ml

woa where is half a liter of coffee a "normal" portion?

Okay, you'll definitely have to explain the NORMAL mug of HALF A LITER!

The reactions to your comment got me curious enough to check. The mug I use for coffee and tea holds almost exactly 400 mL when comfortably full and I used to drink 2 of those per day (across 12 hours or so). Based on that, personally I'd consider ~800 mL of black coffee to be on the high end of moderate consumption.

I’m Irish.

A NORMAL mug of 500ml??? this is insanity to me

Does it matter what size the cup is? Usually you get the same amount of coffee water + additional water/milk/whatever.