We also should really have checked that the old water tower was disconnected from the water system before we started filling it with compressed air.

https://explainxkcd.com/3016/

This comic has been out for 5 days – it is in fact ok for people other than me to post new xkcd comics here too. You don’t have to wait for me to do it. I do it when I think of it and don’t have anything else to do, but wouldn’t at all be bothered if other people did it before me.