This requires a decent amount of detective work and some sweet talking!

Your suggestion of having a professional diagnose - a quick google search for exterior leak detection turns up plumbers, who I am less than thrilled with at the moment, obviously.

They came with a leak detection and determined it was the bath tub spout.

@Anthony HunterI can tell you that my local code enforcement love playing detective with bandit signs to find the owner and give them a fine per sign.Strangely their heavy handed enforcement has worked and you know when you leave the city limit by seeing bandit signs again.

I would start 2 months before and 2 months after.. and if the buyers are buying in LLC's then find registered agent etc.. little detective work but this information should be pretty easy to garner. its all public record..

Take home message is that this is highly contagious, is contagious for several days before the patient is showing symptoms, that patients can be ill and NOT have fever for at least the first six days of illness, and that the blood test for coronavirus may very well not detect it, although apparently nasal and oral swabs do detect it. 

Dogs are the best way to detect, but if you already know you have them, you don't need to go for the added expense.

To piggyback on Mike's Deal of the dayIf you have a vacation rental that has days or weeks where no one is there (maybe just off season)It would be nice to be able to detect a water leak and have the water shutoff.Or lets say you are going on a cruise for a week or so.

It’s difficult to detect and very hard to stop.

Anyone have any recommendations on leak detection devices for their rental properties?