Okay, after some time, I’ve finally got a good working solution for this. However, it’s a bit long and technical, but here are the details nevertheless. Really the Rachio team should look to add a “add on” solution for customers that need to manage unreliable reclaimed irrigation water. Maybe, my case is rare in the global Rachio smart irrigation space.
To begin with, I added an Everydrop flow meter and connected this to my Rachio. When the reclaimed water was unexpectedly shut off and my regular watering schedule attempted to irrigate during this time, then I would get an email and a warning in the app for the zones run with a “Low Flow Detected” warning. However, surprisingly the Rachio software switches to a default estimate mode for water consumption, and my soil moisture goes up as if the zone is watered, when in fact it’s not, because my reclaimed water is shutoff. Seems like a bug, or maybe it’s intentional in the Rachio software for some reason that I can not think of. However, since I got the warning in the app, I knew my grass was not watered (due to reclaimed water not being available), but I have to manually zero out the soil moisture for the zones to get the app to attempt to water on my next scheduled watering window. So not really a good solution, too many manual steps.
My next phase was to step it up and add a pressure sensor to my reclaimed water line and feed the rain sensor input on my Rachio to dynamically disable watering when reclaimed water is not available. This pressure sensor interfaces with some custom electronics that enables/disables the rain sensor input on my Rachio. The custom electronics includes Arduino w/esp8266, LM393 voltage comparator, 5V relay for 24VAC, pressure transducer, 24VAC to 5v voltage supply converter, and Home Assistant for monitoring and overriding the rain sensor input to my Rachio. If the rain sensor is enable, Rachio will not water during the scheduled window. In this case, its not really about whether there is rain or not, I just need a way to dynamically skip watering for a scheduled watering event based on whether I have reclaimed water available. Rachio does not add anything to soil moisture based on rain sensor input, it exclusively uses weather data, and true rain observation data. In my case, I have a Tempest weather station linked to my Rachio for tracking actual weather and rain accumulation at my homestead.
Not sure this will help others, but it may provide some guidance to others with unreliable reclaimed water from a public source using Rachio and what it takes to manage through drought periods where reclaimed water can be restricted due to high demand or become unreliable due to repairs.