Notification of Sensor disconnect

I have a template sensor that monitors for water in the basement at my rental property. I would like to get an “Error” notification if the sensor is unplugged/disconnected. I noticed that when I unplug the sensor, HA just keeps the last value even after a restart. This leaves the impression the sensor is still working. Other entity values seem to go to “unknown” at some point after they drop offline.

Is there a way to tell HA to check to see if a sensor hasn’t reported in x min and return the “unknown” entity state?

-    platform: template
     sensors:
       basement_water:
         friendly_name: "Basement Water"
         value_template: >-
           {% if is_state('sensor.d1mini_1_water_sensor', 'ON') %} 
            DRY 
           {% elif is_state('sensor.d1mini_1_water_sensor', 'OFF') %}
            WET!
           {% else %}
            Error
           {% endif %}

I set them up as binary_sensors and ping them at set intervals. Then I have an automation to alert me when they go offline.