Ice tends to be much harder to absorb by things like dust, which I think the effect of this is, just on a massive scale. So I would say nope.

it has its uses not great

then you look into the math of compressing that much water to a marble then it gets mad like make a whaite dwarf star mad

Bro a bounty hunter in an evil campaign I'm playing just tricked me into drinking a Potion of Aqueous Form to turn me into water and then,  sprinkled dust of dryness onto me. Can't wait for next session!

My players love this item. They fill them up, force feed a poor victim, then gut punch to break it.

Use you imagination to figure what happens when all that water is released.

Or just le it sit in their stomach untill the acid eats away at it.

I am my players broke the Geneva Convention.

Quote from Holvr >>

Quote from DarkThor1987 >>

If a full 15ft cube's worth of water was used to make the pebble, it will have 25,245 US gallons of water to smash in some poor NPC's face. For anyone who wanted to know.

 Which, incidentally, makes this dust tremendously good against fire elementals as well, due to their "water suspectibility" feature:

Water Susceptibility. For every 5 feet the elemental moves in water, or for every gallon of water splashed on it, it takes 1 cold damage.

25 thousand gallons, you've said? Even assuming that not every single gallon is gonna touch the elemental, the damage would still be instant kill on a poor bastard.

Not to mention the sheer force of that much water instantly spawning from a point in space. This is definitely a creative player's item, assuming their DM isn't an uptight RAW worshipper... and that the player doesn't abuse the shit out of this "boring" item.

 

And as a trivia for non-Americans: 25,245 US Gallons equals to 95,562 liters. So, yeah... Nearly 100.000 liters of water you hold in a bead, and can instantly spawn anywhere.

 The Fire Elemental Boss: “You cannot Defeat ME, HAHAHAA!”

*throws pebble*

HAHA-AAAAAAAAAAAAAAAAAAH!!! IT HURTS SO MUUUUUUUCH!!

Also, the Raw worshippers are a real pain in the glutes.

Quote from BaluTheUnBearable >>

1 Ceremony spell creates 1 vial of Holy water / 25gp - hardly efficient for this usage. Unless we include homeopathy and claim that the more diluted the holy is in the water the more effective it gets.

 *Pours a single vial of holy water into the ocean*

Quote from KheldarG >>

"An elemental composed mostly of water that is exposed to a pinch of the dust must make a DC 13 Constitution saving throw, taking 10d6 necrotic damage on a failed save, or half as much damage on a successful one."

How much is "mostly"? I mean, a human is 70% water...

 Probably visibly water based, the “mostly” is so that myrmydons also count.

How does one make some of this stuff? Artificers cannot infuse to create it without DM overruling (*all the RAW worshippers start screaming*, technically they do have a point though, manufacturing of the beads during downtime would be OP) so what is ground to make this stuff?

I have questions about this that don't seem to get answered anywhere. 

Are there any veteran rules lawyers out there with both a sense of RAW and RAI? I am especially looking for your two sense. 

I used a pinch of dust in a sewer hoping to drop it on some mercenaries waiting for us on a sewer platform, as a surprise hoping it might knock them prone or put out some lights but my old school dm made it seem to me like all it would cause is a little splash and be a waste of an item and action and I am just trying to wrap my brain around his line of thinking without being that annoying player. Thoughts on this?

Also...... How exactly does it break? Does it splash outward like a watery fireball expanding from all angles? Does it simply leak from the pearl bead? If it is a 15 foot wall from one side, and that side happens to me a sewer drain that is only 10/20 feet wide is it just the 15 foot length and all the water in that tube? 

What happens if you catch a creature in that 15 by 15 foot water? Do they have a saving throw? Can they break the bead from the inside? Can they live in it if they are a water creature? Do they die via drowning slowly while inside? Could something be transported inside? Could you use air bubble and keep a creature living in there for 24 hours? Is it a pocket dimension or simply a minimized space? 

I have more questions I will add later as I don't remember them at this time. 

Thanks in advance for any 2 cents 

Yeah, someone bites into it and all of a sudden, things start to quickly look like a Starburst commercial from the 90's.

This is a versatile weapon or useful item. Jam it into a NPC ear and smack it their head explodes. have the water blessed to make holy water. It doesn't say the water has to pure you could mix it with any number of things and use them as projectiles. 

Also, I believe it is important to mention:

Raw sewage is also classified as water by any cool DM.

Intimidation works way better when performed in a 15ft room with a 15ft cube of raw sewage at the ready