Try unplugging and replugging your Flume Bridge (the grey device that looks like a salt shaker) into a power outlet. Make sure the white power light comes on when you plug it in (see picture below).

On the Bridge, is the blue WiFi light on (see picture below)? If not, then your Bridge has become disconnected from WiFi. Maybe you changed your WiFi password or you got a new router? If so, click here for instructions on how to reset your WiFi connection.

Try moving your Flume Bridge closer to your water meter. The optimal placement for the Flume Bridge is on a second story with a direct line of sight to the meter. Sometimes this will help if your meter is located outside.

Is your meter in a pit outside? If so, you may want to check and see if your pit is filled with water or snow. If so, you may want to remove as much of the water or snow as possible from the pit. If your pit fills with water often, you may want to invest in an inexpensive water siphon. 

Try recalibrating your Flume Water Sensor. To do so, go into your app. Locate the three horizontal lines at the top left of your screen. Select "settings" > "other troubleshooting". From there, select "recalibrate Water Sensor". Follow the instructions listed in the app to recalibrate.