And don't rely on the destination airport having the same rules when you fly back.

This used to get people doing EU -> London flights. The EU rules had already been relaxed, but you got bitten by the extra restrictions when you went to fly back.

Like most things, flying is a complete shitshow, but do it often enough and you get used to it and all of the foibles.

Regularly flying hand luggage only is a grind as you're at the mercy of the lowest common denominator in terms of rules on what you can carry. When I had to visit a string of customers with one or two flights a day I had to submit expense claims with various toiletries purchased several times over, it was questioned by the finance department and they asked about whether I should check in a bag next time, but they stopped pushing when I said that adding a checked bag to my tickets would have been about 10 times more expensive than just buying things as and when I needed them.

Hugely wasteful but then so is flying, and most of my trips could have been replaced with a video call if it wasn't for touchy-feely corporate politics.

Water: I use a generic cycling bidon for travel. I empty it before security and they're happy with that. Any sane airport will have places to refill it for free, if they don't I can just buy a bottle of water and refill it. No airport I've traveled through has wanted to confiscate an empty cycling bidon and if they did it's cheap to replace.