Why is water so efficient at suppressing the effects of explosions?

SUMMARY: When most experienced explosives engineers first observe an explosion suppressed by bags of water, they are convinced that there has been a misfire. Depending on the amount of water and the way it is contained, the overpressure can be reduced by a factor of ten, sometimes more than twenty. The number of fragments from shell cases can be one hundred times less. Their velocities can be seven times. Slugs from focal point charges are stopped. Safety distances around magazines can be cut. The number of people evacuated from a bomb disposal site can be reduced. In June 1999, engineers from 33 Regiment (Explosive Ordnance Disposal) saved an entire village in Kosovo from the detonation of a 2,000-pound NATO bomb by using water bags.