I say this playing a disc priest lol. The raid trinkets help so much its sad. Other roles don’t have to worry about ooming besides the odd arcane mage.
mage water is inferior to superior dragon spit
When I join a pug, if there is no mage I immediately drop.
I am not gonna spend my hard earned silvers on water.
Yeah Rashok’s helps a lot with mana, but Disc is really great at mana efficiency with just the base spec, and then your 4pc helps considerably on top of that. Disc isn’t quite in “infinite mana never drink” territory like Holy Paladin is, but Disc still has a great mana efficiency in Mythic+. So long as you aren’t falling behind and spamming Flash Heal, you should be doing great on mana.
BYOB unless otherwise stated.
General rule of thumb, having 3 or 4 stacks of water is a good idea, but in general mages should drop a table since it costs them nothing, like lock rocks.
Mage has 1 job… maybe 2… and they always mess it up!
Regardless of if there was a mage in the group, it is the sole responsibility of the player to bring what they need to maximize the DPS, HPS or TPS of the character they play. If that means you need to bring Drinks, Elixirs, Flasks, Food or Potions that is on you. If a Mage just happens to be in the group, and they want to lessen the burden of the group with free resources which are not optimal that is totally up to them, not you.
That said, having them drop a table at the start of the group would have been nice, but did they and you just miss it? As you said there was some language barrier issues as well. So just don’t be a donkey next time and just be prepared, it’s the Boy Scout motto.
I am a warrior so this is zero problem for me.

It’s not toxic to tell you to bring your own water, you should have your own water regardless because there wont always be a mage.
Cuz they’re not prepared

Potions are pretty cheap lately. Nothing stopping you from buying a stack of mana potions or healing potions.
I always just bring my own.
The only time where dps and tank would really sit is if the healer was sitting and even then i usually try to drink as the rest goes into the next pull if i know they can live for a little bit. Having all the dps and tank sit to eat between pulls would be a huge time suck. I always bring my own water because it is something i use. Just like i have my own stat food flasks rune and what not. The cost of drinks are so minimal, do 1 dragon riding WQ and you can probably buy a 600 stack.
This being said mages should always throw a table down before a run. But i always have drinks just in case. It seems silly to expect dps to have them for the healer.
I always put a mage table down. That said, I almost never see anyone take anything from it. By the time it’s down, people are halfway through the instance, it feels. I still put it down just to say I did at the start, and if anyone asks, I drop another.
Three words: delicious dragon spittle.
Healing lfr O.o Almost go oom over there lol. At least on some fights.
Be polite. “Agua, por favor.”
You should always bring your own water (CYOA). Take advantage of a good Mage if you have one on your team, by all means, but never rely on it.