system
Given the following post, respond as if you're commenting on Reddit:
human
[Batman Begins]- Why didn't the water vaporizer in batman begins vaporize the 60% water in humans?

In the Ship scene you see it vaporizing water everywhere around it, including right beside people running around, but they're only hurt by the steam right beside them and not the weapon itself?
gpt
The ionizer specifically reacted with water in contact with the heavy metals associated with Gotham's sewer system. 

It's most effective against water in a pipe, as the rays bounce around in the pipe to vaporize the water quickly, though it works okay on a basin where just the "tub" is metal.

People don't surround themselves in metal, and even if they wore a lot of jewelry or were in a metal building, those materials are not the same ones used for plumbing and pipes, so they were safe.