Taco make a thing called the"Wags" valve for gas water heaters (water & gas shutoff). Which is activated by moisture.
Another is the "waternogovalve". This one is manually operated by flicking a switch, but I'm sure can be adapted to automatic by incorporating some kind of sensor and relay.
I believe Taco's site is www.taco-hvac.com
The other is www.waternogovalve.com
Good luck in your search.
Oh! you could also do what our other bud suggested, and type in key words in " " at www.google.com
Have a flood-free week.
Brian in Swampland (no leaks, just swamp :)
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