What I want is something that detects the presence of water, and sends a signal. It will be used to detect when the main drain in the basement gets clogged so that I can take preventative measures before it gets out of control. Ideally this switch could be interface from my computer via USB, and I can then program it to send me an email when it goes off.
I am not looking for a canned product that costs in excess of $100! I am not an electrician, but I am a computer programmer and I want to be able to do all of that part on my own. There has to be some kind of low-level sensor out there that I can hook up how I want. There ought to be various ways to intercept the signal from said sensor. Once I have a sensor and a way to read the signal from it, my possibilities are endless. I am just trying to get to that point and I have no clue where to begin.
There are 25+ year old sprinkler systems out there that are smart enough to not go off when it rains. I asked a local irrigation expert who installs and maintains these systems, and he says the old ones have an analog sensor that you typically mount on the roof, it contains some kind of rubber element that swells up when it gets wet. The swelling causes it to press a button. When the water evaporates, the swelling goes away and the switch gets flipped again. Now that is old school and certainly not rocket science, but I have no clue how to devise such a thing. That is why I am here.
I have answered a lot of questions on Stack Overflow because that is my area of expertise, just trying to get some love back here in an area where I am clueless!