Flood or moisture sensors detect the presence of water. Typically they are used for detecting leaks from pipes and appliances. They are often money well spend because undetected leaks can cause huge amounts of damage. A leaking pipe in a loft can bring down ceiling and floors, destroying precious, personal possessions in the process.
We also use soil moisture level sensors as part of our automated irrigation systems. These don't provide a binary output indicating the presence of water or not, but provide a percentage value indicating the level of moisture present.
We use common models for all the sensors and all the types of sensors connected to our Home Control System. Combined with technology abstraction this means that any sensor added inherits all the capabilities supported by each model and our smart home. Essentially, every sensor connected becomes instantly very smart. They can all generate or voice announcements if required or trigger an alarm.
Flood and leak sensors need to be installed where they are best likely to detect any leak, so ideally right under any potential source of leaks. This might be under bath or shower plug hole, under a washing machine, dishwasher, etc. Sometimes it is beneficially to place them on some kind of a tray, to help bring the liquid to the sensor and effectively allow it to cover a wider area. This 'tray' could also be a sheet of plastic.
Flood sensors are the kind of things you want to fit and forget about, but know that when the time comes, they will alert you to any problems. For this reason we have connected cheap, reliable and 'dumb' sensors and most of them are wired, to avoid the need to worry about batteries. The use of cheap, wired, binary sensors means that we don't have to worry about technology obsolescence.
The same circuit is also used to detect high and low water levels in our pond.
There are wireless flood sensor available but they are quite expensive and require batteries. None of the ones that we have tested will work with very pure water, such as rain water.
We have developed our own wired flood and leak detection sensor which has been designed as a low-cost, extremely reliable sensor for new builds and to also retro-fit into existing buildings. It is easily interfaced to many things including legacy alarm panels and the smart home.
In our contextual smart home all of the leak/flood sensors will trigger the alarm and result in a voice announcement, telling us which sensor triggered it an where.
