You can go the cheap route and just get a Zwave moisture sensor that has an external sensor such as the Dome Leak Sensor DMWS1. I have one attached to the wall above my sump bucket and then have the external sensor going through the same hole as my pump power cord but have it hanging well above the water but not near the top.
Then I have a rule that will notify me if water is detected so I can investigate.
Going another step further, and more expensive, I purchased one of @iharyadi's environmental sensors (which he is unfortunately out of at moment) and have that connected in the same plug as the sump pump. It has a battery backup and if it detects a power loss, it will notify me that the sump pump power circuit has no power since this circuit is on a GFIC breaker. My hub, router, etc are hooked up to a UPS so even with a whole house power outage I should still get notified assuming my fiber service is still online.
Given the availability of the environmental sensor you can read this thread of my original solution using a 5v relay and a contact sensor for power monitoring for my sump pump. I ended up moving this to another circuit in my house since the Environmental Sensor also gives me humidity and temperature data within my crawl space that the contact sensor did not.
