Open sprinkler to switch between rain barrel and city water with float switch

[Gompka]

I have been using open sprinkler for a long time and it has been running great. I have a diy setup that runs 3 zones. Recently I have added a large rain catchment system with tank and a pump to pump rain water into the sprinkler system. Is there a way for open sprinkler to switch from rain water tank to city water based on a float valve input? Or does anyone have an idea how to design such a system? Basically, if the rain tank is empty I need the system to switch over to city water for the remainder of the watering period. I use homeassistant and offloading the logic to homeassistant may be an option.

[bekesizl]

I use a PLC for this purpose (that was already used for different automation tasks in my house).
The general firmware of the OS is not able to do this task, but you might be able to do it with a relay or a smart relay with Home Assistant.

I have two floating switches in my water tank.
The lower one tells me, if I have to refill the tank.
The upper one tells me, tank is full (enough) for some sprinkler use.
Filling is timed at night before sprinkler operation. This way if enough rain is falling, the tank doesn’t get filled.

The tank is for gathering the rain from my roof.
But can also get filled from the city water supply via a standard sprinkler valve.
For driving the sprinkler I always use a pump, switch on with a flow switch. It builds up a pressure in the tubes and tries to maintain that. If a valve is opened, the pressure drops and starts the pump. After a valve is closed, the pump runs for a short time and switches of when the pressure is built up.

[Gompka]

Interesting idea, I would like to avoid having to fill the tanks with city water if possible. I will have to investigate with homeassistant then. I have 4 ibc totes right now and use a pump, turned on manually for watering.

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