This is just a friendly and helpful note to all Warlocks in dungeons and raids.
Before entering fill a bag with drinks, then immediately upon entering the dungeon or raid. Give it all to the healers.
Life Tap has to be the most annoying spell for healers when grouped with Warlocks.
Last Sunken Temple run I healed (a couple of days before this post), I spent more mana healing the Warlock than I did the tank, myself and the other two dps there.
Why should i buy water? I have life tap and drain life
I try to limit my life tapping and check healers mana whilst doing so, or ask the healer if they mind. Usually they don’t mind but I still stop and drink. Aome People just don’t think about it:(
Fully agree with OP. Most locks are totally clueless on how much impact life tap and conflagerate (what’s wrong with rain of fire?) have on healer mana. I’ve adapted the following on my priest and Druid when healing dungeons:
Can’t recall ever seeing a warlock use drain life or a health stone in a dungeon to negate life tap/conflagration, it’s all too easy to rely on the healer so you can pad your numbers…
In raids I usually get topped up after life tapping before I can get a single tick of my food/water that I use immidiately after life tapping to 50%-70% mana, then another couple of thousand overhealing follows. Same in dungeons on a smaller scale. Also, bring a mage.
Aren’t healers there to, you know, heal everybody, not just the tank.
Besides there are so many mages in any group, who needs to buy water?
Well, i always said healer to ignore me if i life tap but it never works, they keep wasting mana… so not my problem anymore.
There’s two sides to that coin.
Sometimes warlocks completely disregard any mana efficiency and blow their mana into oblivion, then relying on lifetap and the healer to get them back to normal.
Sometimes healers don’t realize what’s best for the clear efficiency and are too bltchy about having to heal someone other than the tank.
Because in the meta we are playing everyone is all about the RUSH RUSH RUSH life…Rain of Fire is pretty poor damage AoE wise and Hellfire clears things a lot faster obviously it’s on the lock to know when to stop using it if things are going south but generally it’s going to be better.
No offence but Healers often have the easy life with not needing to heal all that much during dungeons
Tip to healers, in between pulls before you drink put a HoT on the lock. As a lock player I can tell you theres nothing more annoying than a healer who only heals the tank, slows the run down massively.
It’s fun when there’s a not so geared tank and two warlocks… 
I appreciate it when warlocks use bandages and healthstones and such, but at the same time it’s no issue at all to throw a heal on them. The only thing that can get me grumbling a bit is when a pull went obviously bad, and then on top of panic healing they start to life tap happily to like 10% health. Eep!
Conflagrate? what has this spell to do with healers mana? I think you talk about hellfire. fyi Hellfire costs less mana, does 50% more dmg than RoF thats the reason its used, and overall there is only a problem when its not talked beforehand.
Allways depending on the grp, i usually cast Renew on warlocks and with that they need to manage their hp for themself.
Or like any sensible healer going into a dung u can ask a mage for water.
Warlocks have retarded mana costs for abilities but i dont see any1 crying about mana when we summon ur lazy azz from the other continent.
Dont want to heal life tap? Then dont but stop crying about it in party or on forums.
Only problem I have with life tap is if they lifetap between pulls, like bruh… I’m not gonna heal you, if you’re not even eating after life tapping… whilst I’m drinking.
I drink for mana > they lifetap and don’t eat > I have to waste mana to heal them AGAIN > I have to drink again.
It’s literally the only problem I have with some warlocks.
Like all healers, I do ask the kind Mage for some water. We had no mage in the group, so no extra water. 
It’s interesting to see that this, like so many other things in the game has some people politely discussing and others not.
Tip to healers, stop throwing your big heals at us when we tap. I make due with a renew once in a while, no need to keep me at 100%.
Me who feels useful with warlocks around as a healer : o_o
Eat? Bruh, one of the main reasons to play warlock is not having to do such dull mundane tasks as to carry & use stuff like water/food.
Just don’t blame me, if you don’t get healed as you refused to eat/drink whilst your healer’s drinking.
Nah, it’s easy to selfheal as warlock during combat.
Yeah, a lot of them don’t and continue aoeing lol.