Utilizing the fact that ruuvi tags report angular position (from the Z accelerator readings) I have taped one in a swinging position to the discharge pipe of my sump pump just ABOVE the maximum water level. It reports to the RuuviCollector running on a raspberry pi. If the water level reaches the tag it begins to float and changes from a vertical position. The influxdb is queried every 10 minutes from a cron job. While the tag is positioned nearly vertically a small absolute value ( like .004 or -.004) is returned otherwise the tag is floating.
This is the same idea I used in the https://f.ruuvi.com/t/garage-door-monitor/3800
An interesting (but not very useful) side note is that when the pump does operate the movementCounter increments.
Let me know if you want to implement this or something similar and you lack the database or linux skills, I’d be glad to help you.
Once you have a ruuviCollector pushing data into an influxdb it is amazing the number of application you can run just by “sticking” another ruuvi somewhere!