Need the ability to choose less than 1/8 inch rain detection

The new mandatory California statewide water restrictions says that you cannot water within 48 hours of any measurable rainfall, That can be as little as 1/100 of an inch. However, the Rachio scheduling interface only lets you go down to 1/8th of an inch. This is not enough. For example, it rained 0.04 inches here on Thursday and on Friday the Rachio irrigated, which is against the rules. Please create an option to be compatible with California watering restrictions.

Hi @Stereolab42, good morning. Thanks for reaching out and sharing your concerns with us.

I’m curious if we can find an actual measurement from the State of California on how low of a threshold we need to set to be in compliance. I’ll do some digging, but if you stumble across anything, please share your findings with us.

One idea might be to add the ability to delay if we observe OR predict ANY rain, regardless of the total…thoughts?

Best, Emil

Yes, any rain at all counts, no matter how little:

We have micro climates here so it could easily be raining in one area and not in another. Doesn’t this mean I need to get a rain sensor? Is it possible to install a wireless rain sensor now for use with Rachio?

In other words, tweaking this feature based on a weather station not near me will not be in compliance.


Thanks for the reply. You can certainly utilize a rain sensor if you would like. The Iro will function with both a wired and wireless rain sensor. If you want to review this article we review Rain Sensors and have wiring images for the main wireless sensors.

You could also potentially use IFTTT. I am not sure if you have heard of this but it is a third party software that we are integrated with. We have other California users that create a recipe where if the weather in their area changes to rain the Iro will begin a rain delay for 48 hours. This way you are in compliance with the 2 day rule if there is any rain.


IFTTT looks very interesting. I created a recipe for a 48-hour rain delay and will see if it works.

We are going to look into a weather intelligence setting (virtual rain sensor) for any precipitation. This will be in addition to 1/8, 1/4, 1/2, 3/4, 1 inch settings. Hopefully we can squeeze this into v 2.0 of our software being released in May :wink:

Maybe you missed what I wrote about having micro-climates here such that rain in one area does not mean there will be rain in another area. So unless I have a rain sensor where the Rachio is located, technically most people will eventually not be in compliance. IFTTT nor any other feature will fix this.

Sorry, missed that part.

Correct, a rain sensor will help in micro-climates. Also, in the app we allow you to enable using personal weather stations. While these can provide much more localized data, be wary when opting in to use them. I’ve seen a lot of instances where the data is of bad quality.

In the next version of our app (2.0) we will allow you to choose a preferred weather station to use.

So, if you know and trust a nearby PWS, you can choose it ahead of time.

Hi @radamio, good evening.

A rain sensor has it’s pros and cons:


  1. It’s on site – no microclimate concerns
  2. Cheap and easy to install


  1. Only reactive, not proactive (i.e., a rain sensor will only interrupt the common wire once it’s wet – it will not skip a watering schedule based on future rain)
  2. Limited functionally – it can only interrupt the common wire.

All things equal, if in doubt (or concern), a rain sensor is a cheap insurance policy if you want to make sure the Iro never waters in the rain. While we’ll be adding CA restriction rules to the app, this rain sensor can be programmed to interrupt the common for up to 72 hours anytime it gets wet (it’s also super easy to install). Combine that with the predictive skip functionally of the Iro and you’ll always be in compliance.

Hope this helps :blush:

Best, Emil

That makes sense, I’m going to try this out, thanks for the explanation.

@radamio – happy to help. Please keep us all posted on your experience.

Best, Emil

I read the following:
“To prevent severe equipment damage, never connect the Rain Sensor to any power source greater than 24 VAC.”

I’m connecting the Rainbird WR2 to the Rachio, so how does that relate to the power source? If you know that the rain sensor is connected to the Rachio, then presumably you know if it’s greater than 24 VAC, so why even write that?

Or do you mean never connect the Rachio to a power source greater than 24 VAC if a rain sensor will be connected to the Rachio? I’m confused.

@radamio, I think you found this statement on our rain sensor article, correct?

Good question, the WR2 requires 24VAC to power the transmitter than connects it to the rain sensor.

Correct, but some people do some interesting things with wiring :wink:

Nope, the Iro requires 120v input, but outputs 24v.

Hope this helps.

Best, Emil