Flood Detector Solution Neede

Hi, apologies if this may of been duplicated before but I cannot find the answer I require.

I have a client with a Visconic Powermaster installation and they require a flood detector..... Easy I thought as they are listed as an option, but buying one is a problem as they are not available in the uk for the powermaster. Having spoken to Visonic there are no planned dates they can give as to when it will be released.

In the meantime I am thinking I can use the aux input on the door contact module and hard wire a flood sensor to that... Does anyone know of a suitable sensor with a N/O output contacts that would be suitable. (There is NO provision for power in the basement so looking for a passive device)

Thanks in advance.