There are several. I have one as I mentioned in my comment: it's called a Phyn Plus. It works with and without sensors. I have some in strategic places like under the water heater.
It actually caught a leak, although it wasn't from the plumbing. It was rain getting into the chimney and dripping into a puddle in the boiler room that set off one of the sensors. I like the cable-style sensor they have -- it's like a 4-foot-long headphone cord, but the whole length is a water sensor, so if any part gets wet it goes off.
Not being able to exit your home in an emergency without a key is a serious safety problem. In most places it is not permitted.
International Residential Code R311.4.4 “All egress doors shall be readily openable from the side from which egress is to be made without the use of a key or special knowledge or effort”. Most local codes are derived from this.