Precipitation rate given gallons per hour data for a zone

I installed Rachio yesterday and learning all I can to make its flex schedule more accurate.
From the threads of these forums, I get that I need to do ‘catch cup’ test to get reliable precipitation data.
Instead of this, can I do the following?
I can measure number of gallons of water a zone used in given time ( say 5 minutes) by noting down the water meter numbers outside the home.
Given this info, is there a formula to determine the effective precipitation rate (I.e. In per hour) for that zone?


Does the formula given at be used for this?

Basically what it says is:
Precipitation rate = (96.25 x Total GPM)/Total Area

I know the approximate area of each zone.

If this is good enough, how do I input this info into each zone?


That formula will give you a good starting number. The catch can test will give you more accurate results. Once you determine your precipitation rate, make a custom nozzle using that number and apply it to your zone. HTH.

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As an engineer, I don’t agree that catch cans are more accurate. They only give data on a very small spot. The formula from Videoguy is far more accurate. If you don’t think that you have even coverage in your zone, then decrease the efficiency some. GPM from a meter with a good area coverage measurement is the way to go.

I’d agree that the meter & area is a good way to go for a flat precipitation rate. My previous response was a bit inaccurate. The catch cans go an extra step & give you an aspect of zone efficiency which plays a fairly large role in how the run time is calculated to cover the ‘critical’ area(s) while over watering the rest. I’m NOT an engineer though. :stuck_out_tongue_winking_eye:

This is great. Be careful to use the right units in your calculation. To use the 96.25 factor, your measurement must be in gallons/minute divided by area in square ft. Multiplying that rate by 96.25 gives you inches per hr, which is the unit required for configuring a custom nozzle in the Rachio app. You can create a custom nozzle on the phone app by swiping the screen to the right or tapping on the 3-line icon upper left of iPhone screen. Then choose “Custom Nozzles”. Label your nozzle something like “1.65 in/hr spray”. Then go back to the front page swipe down to the “My Yard” banner and tap the zone you want to change. In the nozzle field, the new custom nozzle will show in the drop down list, and you can pick it. Also update the square footage field so that you can get a more accurate reading of gallons used. Good luck!

Well put, I whole-heartedly agree. :smile:

I configured the Rachio as suggested above. Now the water usage seem more accurate. We made many modifications to Lawn after builder installed the sprinklers. Yesterday I tuned all the rotors to cover more of the zone they belong to. That should improve efficiency. The Rachio app came pretty handy to turn the sprinklers on or off from the lawn without having to run to Garage :smile:
We had Flex schedule kick in today for the first time. Now I have better idea how it works. It is pretty smart. It didn’t water all the zones that were included in the schedule. It picked the ones whose moisture level is below a threshold and watered them.
I was little bit concerned at first with the estimate that the Flex schedule shown. Now I understand that it is the worst case estimate. Most of the times, the watering time might be lot less. Mine showed 330 minutes to cover 8 zones. But it ran only 130 minutes today to cover 4 zones I believe.
So far I like it.

Thanks for awesome product!

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Just an FYI, the watering times per zone will not change, just the frequency. If you feel these are too high/low you can go into each zone in the flex schedule and use the water adjustment dial. If you have any questions regarding flex just let us know. If you are bored, here is some good reading :wink: