Heh, we do the same. I appreciate that Changi airport has bottle-filling fountains at every gate.
I really appreciate Haneda airport for having bottle scanners, so you can just bring your filled bottles through security. Saw this at an airport in Europe, too, but can’t remember where (domestic Athens maybe?).
If you find this kind of humour humourous, look for “Look around you”. It’s around on YouTube so go take a look!