I’ve encountered several healers lately who don’t even bring their own water to instances and expect there to be a mage. Why do they not bring their own water? They then try to do the instance without drinking but they can’t manage it because they go oom.
What are they even thinking?
Most healers do have water. But when there is a Mage its simple to ask a mage for water, its cheap, saves time, gold,
Honestly, am guilty of this sometimes, on both priest and druid.
Simple answer is I forgot, because I was making/buying food, flasks, pots, runes, scrolls.
Sometimes I get summoned while I’m in the AH window and the summon popup blocks the next page button and if I don’t want to cancel the summon and ask for it again I have to buy whatever is on that page, regardless of price.
Coconut water is 2 gold 50 per 5 in the pyramid 
it costs ‘nothing’. I always stock up to 40. The turtles on the right on the map in zuldazar sells for 2 gold per 5 by the way. But I am lazy and do not fly there.
Cause when you heal several runs consecutively, it’s only natural that you run out of water at some point. Only ways to deal with that are either to frequently go to some nearby place to get water (something of which you can quickly grow bored, and willingly forget about) or buy a lot of water in one fell swoop, but then again not leave enough room in your bag which can turn out to be quite unpractical.
On my healers I drink so few times that I always forget to restock my supplies. So guilty.
Often run with a mage too, so that mitigates my failing memory.
Best part is when you find you’re without water in tol dagor.
“Oh there’s a fp just outside, has to have water”
Nope
“Let me fly to the pirate den and buy it there”
Only alcohol is sold there
Then you’re like wtf, I’m gonna have to nag ppl to resummon me…
Thats because only healers have to drink and most people play healer as secondary thing that speeds up queue. If all casters would had to drink then knowledge would be wider~
I would not buy water as well 
Simply put - most “healers” are offspecing.
Being DD requires you to forget mana exists - when you go in as a healer you forget to bring mana drinks.
Courtuesy of a leader would be to have drinks on him and sell it to the dumbass healer like me, but well. That’s how the game is.
You can’t trade it cross realm.
I used to keep 2-4 stacks of water on all my characters capable of healing. It used to not be a big deal.
However, Mechagon and Nazjatar and offspec Azerite Armor and WQ azerite armor I can’t vendor and random scrapper materials and raid consumables and war scrolls and random materials I get from follower missions and random greens I have to keep to scrap and fish I opened in the box I got from Arena and mailing hundreds of bracers between characters for Expulsom generation and all the collectables you get to turn into essences and all the essences you have to keep in your bag until your next trip to Magni and basically the insanity that is the entirety of BfA obliterated my bag space in a way that I can no longer afford to use the three bag slots for water just in case I get the urge to offspec as a healer.
Blizzard? Account-wide bank when? Remote bank access toy/mount when? I’d like to be in a raiding guild and I’d like that to not be mutually exclusive with convenient multiple character storage, I don’t think that’s an unreasonable thing to ask…
Wait, even when you’re in a party?
What BS is this then? 
Don’t mind me then. Move along.
Nope, only conjured items can be traded cross realm.
I usually buy like 200 water. Sometimes i havent noticed that i’m running low and should have re-stocked before starting the dungeon. Most of the time i have a monk in my grp that can trade me some water if i forget. I dont think it is a common issue though, most healers knows they need to drink. More annoying with ppl that dont bother bringing some food to help bring the health back up every now and then in griev and bursting weeks. Would let the healer spend the time drinking instead of having to heal everyone and then drink.
Healers I have been with tend to forget. Some play healer only in M+, or only in raid and do forget to resupply, when they go to one or other. It is perfectly normal to be absent minded.
Have you tried asking them? After all, they are the ones that would know.
Sometimes, I ask myself if Activision Blizzard doesn’t do it on purpose …
So you now have bigger bags ?
Time to create more junk to fill them up with.
It’s almost as for each convenience added to the game, they needed to create a inconvenience …
Cheers.
They stockpile water but when they log off it disappears 
When levelling at least, since you spend more time in a DPS spec that doesn’t need water anymore, it’s easy to forget to buy it as you’re levelling. More than once I was stuck in a dungeon OOM with water that was like 30 levels below me.
Not sure how people can forget it at 120 though.
1: When lvling up, its rare healer go oom…so, they dont learn to take water with them…and say they do go oom, they are proberly about to ding anyway = not oom anymore!
2: If they do buy water while lvling, they might out lvl the water they got = they find it useless.
3: Be a team player yourself and farm them vulpera reputation, get exalted+ chest, get [Goldtusk Inn Breakfast Buffet]…your account now have a 10 min CD toy that give any player “water” (at any lvl).
Any lvl and class can use this toy, even your alliance alts! (even tho the toy is locked behind horde rep).
If there is anything i am supriced by, its the lack of healing from hybrid class in BG’s (The AV event), its no shame to heal ppl who cant heal themself with some off heal you know?, did ppl forget that they can do that?, or, they dont know that those heal they have can be casted on other?