Not that new. If I have read the article correctly, this is actually recycled water. It was carried into the mantle as oceanic tectonic plates were subducted.
Previous predictions calculated that if a cold slab of the ocean floor were to sink thousands of miles into the Earth’s mantle, the hot temperatures would cause water stored inside the rock to evaporate out.
“That is exactly what we show here,” Wysession said. “Water inside the rock goes down with the sinking slab and it’s quite cold, but it heats up the deeper it goes, and the rock eventually becomes unstable and loses its water.”
The water then rises up into the overlying region, which becomes saturated with water [image]. “It would still look like solid rock to you,” Wysession told LiveScience. “You would have to put it in the lab to find the water in it.”
Bolding added
And, as the bolded sentence indicates, you couldn't fill a bucket with it. Or rather what would be in the bucket would be rock. It would take a laboratory analysis to find the water molecules in it.
The researchers estimate that up to 0.1 percent of the rock sinking down into the Earth’s mantle in that part of the world is water, which works out to about an Arctic Ocean’s worth of water.
What I see again here is creationists' lack of attention to detail. Did you just read the headline and not the full article?