Rain Barrel status

Any ideas how I can monitor the status of my rain barrel? I have a 55 gallen barrel and I’m looking for some type of sensor that can let me know it’s filled status (0-100%.)

If you’re a DIYer…

A year or two ago I built a water tank depth sensor using an Arduino. Getting the level reading from the Arduino to the LAN was fiddly but is a generally solved problem (serial or Ethernet). In the end I disconnected it; the readings tended to drift (also, the drought ended, so the need for sensing was less).