FYI:
THIS Winland WaterBug is kind of intriguing. From that site's specs:
The model WB-800 operates on 12 or 24 Volt AC/DC and has a form C relay output that can be connected to alarm panels, bells, dialers, etc. Unit also includes internal alarm buzzer with silence switch and eight LEDs on console to identify the sensor in alarm. As many as eight supervised sensor probes can be run up to 500 feet away (or 16 non-supervised sensors). Each sensor probe has two contacts. When a film of water forms a bridge between these contacts, the unit senses this and triggers the alarm output. The sensor will not alarm due to condensation or high humidity. Four standard surface sensors are included with the unit.
This way you will only have to use one Elk Zone and can run your probes on "hopefully" just two wires (couldn't find any info how may actual conductors were required to the sensor).
Of course you would not know "which" zone tripped, just that one did.
Anyways posting this just for the fun of it.
EDIT: Scratch that. They want over $300 for that unit!!!
Something like
THIS has a lot better price (even though it's not an apples to apples comparison).