How does the flow sensor work for Gen2?

  1. Awareness of water use (current estimates would be fine for this)

  2. Accurate water usage to compare to bill (we had some folks in neighborhood had super high water bills. They put a meter in back of the city meter and found the city meter was off by a significant amount).

  3. Leak detection - shutdown/notification

Also, while a leak in the sprinkler side of the valve would need to be quite large to be noticed, a leak in the pressurized side could be small and still add up.


i suspect this at my address as well…


The main reason I want a flow sensor is to calculate how much water I’m putting down in a zone. If I put down 100 gallons in a session watering a zone that is 1000 sq ft, then I know I put down 0.1 gallons per foot. Doing some math, I would calculate the number of inches of water that is and use that to adjust my run times. That way I know if I’m putting down 1" per sq ft per week, etc.


I have a 24 zone system that I would love to be able to use a flow sensor with. Will there be a way to do this? I am thinking that if one clock is running the other will think the system has a broken pipe. In this system I have a few zones that take about 10 seconds to turn off while the next zone is on (kind of like the anti hammer function only this is a very slow closing valve.) will there be some kind of delay in sensing the flow in the zones so It is not setting a baseline with 2 zones on.

If I can make it work I will need it to go up to 3".


We will only be able to detect individual zone runs for the device where the flow meter is installed. Anything else will just be viewed as flow. We can’t make a correlation at this time. Could it be done in the future? Yes, but I don’t know when, if ever, that would be built.

Hope that helps.



I’m in the same situation with 24 zones and would like to monitor my water flow. If you guys put combining two controllers into one system back onto the software roadmap this would be fully accomplished.


Until they do that you are stuck with a hardware solution


@plainsane, that’s an awesome find! Thanks for sharing it with us :smile:


Well your ee guy posted a document that references it, I just highlighted in case it got overlooked, but I still take your electronic high dive and run with it.

But he deserves the credit


It would also let me use a 24vac supply for the meter I’m considering :smile:

Any word if it would work with a pulse counting meter or if a flow meter is sampled occasionally?


Great input here. Thank you for the listing of Sensors you plan to support. I will definitely need a higher diameter valve… likely 3 or 4 inch as I’m using this for my small farm. I presently run a pressurized system where my pump runs on a pressure switch and the system is maintained at a steady 45PSI. When one of my valves are opened by the controller, pressure drops and the pump kicks on to maintain the pressure levels until reaching the max pressure of 45 PSI. I had planned to install the flow sensors on the main line leaving the pump and entering the constantly pressurized loop I have installed around the property… thus whenever the pressure drops in the system outside of a normally scheduled watering event I can be notified.

I haven’t chosen a flow sensor yet- I was hoping to get a sense of what would be supported before purchasing and installing. Any suggestions amongst the list provided by Franz (Bearing in mind the potential size I will require)

I’m not sure how this data would integrate/Display on the software/GUI side of things…

Lastly, I emailed my water bill to your marketing guy… I’ll try to post it on here somewhere if I can get my phone to upload.



I’m still looking to see what, if anything, a sensor that is installed as we’ve discussed to the Gen2 controller, will do, right now. Anything? Is any information gathered by it, or is this merely an appliance to be installed for promised support, hopefully this summer?


Currently it will not do anything.

We are building the software that will measure, aggregate, and persist flow data. Eventually it will be used to render reports, calibrate zone precipitation rates, and some other fun things.

This will not require a firmware update. Our cloud infrastructure is being built to manage and store this data.

Hope that helps.



I have a simple pump based residential sprinkler system. I am looking at purchasing a smart controller, and the Rachio Gen2 is on my short list. But, I would like an affordable flow meter to use for a few purposes (listed in order of priority).

  1. Protect my pump and solenoids from overheating when there is no flow (shut off if the flow is too low). Solenoids go bad, and when there is no flow, it can damage the pump due to overheating because water flow keeps the pump cool. If the pump goes bad, I don’t want the solenoids to be damaged due to overheating with no water to help keep them cool.
  2. Help in recognizing broken pipes and sprinkler heads, and shutoff if the flow is too high.

In both cases, I would like some sort of obvious error indication on the panel and possibly an error email.

On the subject of affordability, all the sensors on the list so far are expensive (>$200 with the sensor T included). Why not also support inexpensive (<$30) 3 wire flow sensors, such as the ones sold by TmallTech on Amazon? (Search on Amazon for TmallTech flow. One size is shown at the link below.)

It is a pulsed output, but requires power. Even if an external DC power supply is needed (not supplied by the controller), and even if an external electronic switch is needed to mimic breaking a contact to simulate a 2 wire sensor (not sure if that is necessary - depends on the controller interface), that is still MUCH cheaper than the expensive flow sensors.

I have also considered to adapt in (via a T) an inexpensive paddle-type flow switch to protect in the no-flow situation, such as this one at Amazon:

I could connect it into the second rain sensor input, or in series with a rain sensor if I use two rain sensors.

In both the flow sensor and flow switch cases, the controller would need to wait 15 to 60 seconds after the pump turns on before deciding if the flow is correct.

I have only found one residential controller that does the above, but you have to spend yet more money on another interface module to read the flow sensor (which makes the total cost more than the Rachio Gen2), and it says it only supports 2 wire sensors. I could make the simple circuit to convert 3 wire to 2 wire, but I would prefer not to have to do it myself.

On a related item (pump protection), I would also like to attach an inexpensive temperature switch to my pump and/or motor housing, and have that signal go to the controller so it can read that there is an error and turn off the system. A simple bimetal temperature control switch is cheap, and can be bought at varying temperatures from Amazon (for about $9 for 10 switches).
Again, I could put it inline with the rain sensor or a flow sensor to cause the system to be shutoff, but it would be nice if there were a separate input so the error source could be identified. (I could build an error status indicator circuit for this, but I prefer the controller to do it.)



Thanks for the input on functionality of the flow sensor. The plan is definitely to implement those types of features for the flow sensor, but for us the first release with flow sensor support will just be used to link flow to actual usage (as Franz mentioned above). I can’t say for sure when diagnostics will be released, yet. In terms of the low cost flow sensor, I can only tell you that the current plan is to support the flow sensors listed. When that’s complete we can look at a low cost sensor. I believe the one you mention uses British pipe thread. If you’re in North America, you’ll want to find one with NPT threading or you’ll have trouble finding fittings. It’s frustrating that there’s a lack of low cost irrigation flow sensors at this time, but I believe that will change as more consumers are asking for flow.

On the flow and temperature switches, I don’t think we get those requests very often. If there are two wire versions or a 3-wire that accepts AC power, we could theoretically support them. I can’t make any guarantees when something like that would make it into the software, though.



Thanks for the quick response.

In regards to pipe thread adapters for the inexpensive flow sensor, PVC BPST (G thread) to slip adapters can be ordered online, such as at the following:

I suggest you also allow a user defined flow sensor type in your user interface where the user inputs the number of pulses per gallon. I have a garden hose valve on my piping just before the sprinkler valves, and was thinking to just see how long it takes to fill a 5 gallon bucket, and use that information to set the pulses/gallon to the right value. (For user calibration, enter an initial estimate of the pulses/gallon into the controller, define the valve as a zone not connected to a valve (or disconnect a valve), open the hose valve, turn on the test zone via the controller, monitor the flow rate reported by the controller and wait for it to stabilize, move the hose to start filling a 5 gallon bucket and time how long it takes, then use that time to scale the initial pulses/gallon value to the proper value.)


Looking to add a flow sensor to my setup, does anyone have any recommendation of one these over the others? Pros / Cons? My supply line is 3/4" copper until after the vacuum break outside.


I’ve reached out to our hardware guru @alcornb to see if he has any recommendations.



I believe all the flow sensors we recommend are pretty similar. The things you’ll want to focus on are getting the same diameter flow sensor as your supply line and making sure the flow range of the sensor covers your expected flowrate. The Toro TFS-075 may be your only option in 3/4". You’ll have to get some fittings to go from copper to PVC, but you should be able to find what you need at a local hardware store. Most irrigation pros install these underground, after the backflow, where the pipe is PVC or poly. However, I don’t think there’s any reason you shouldn’t install above ground on the copper if it’s easier for you.


Thanks, I’ll look into the Toro. The copper would be easiest since it is inside and close to the Iro. Another question, what does the Iro do with flow sensor data when it is not actively running a zone but flow is detected? I have spigot on the same main irrigation line. This may influence whether I put the flow sensor on the copper inside the house or outside after the backflow on poly which is 1".