New setup questions - re: gallons used calculation


Had an IRO in my previous home which I left with the new owners. Finally replaced the one which came with my new construction home. So, my 2nd time around. In the new (Calif) home, landscaping is not quite Zeroscape but is a mix of ground cover, bushes, roses and trees and lots of bark covering. I will likely preset specific watering days as we have restrictions to certain days per week and may use some portions of the flex.

I am trying to get good estimates on water used. The entire system uses 1 GPH emitters on everything. The irrigation install follows a standard, ie: 1 emitter each for small ground cover plants and other small plants, 2 emitters for the larger bushes and 4 emitters for the trees. Therefore I was able to estimate # of emitters for the whole landscape at about 270 emitters. I do know your system does not consider the # of heads but works on sq, footage and the output of the head in your water used calculation.

I did create a custom emitter per your formula, which came to 1.6 in/hour. I decided to set the landscape to perennials as it was about in the middle of all of the choices. I left the default of 500 sq. feet in each zone (plus all of the other defaults in the advanced area.) and ran a test. 1 minute in each zone. The dashboard calculated 17 gallons used combined for both zones. Because I know the # of emitters and GPM, I can roughly calculate the water used for 1 minute to be approx 4.5 gallons, quite a disparity versus 17 gallons.

I think inputting the actual sq. footage of landscape area of 2600 sq. ft. will make the computed gallons used much worse, correct?

Wondering if the best approach is to lessen the sq. footage until I roughly meet the # of gallons I have manually calculated? Could I do a rough calculation such as:

4.5 gal is 26.5% of 17 gallons
Therefore 26.5 % of 1000 sq.ft (500 zone 1 and 500 zone 2) would be 265 sq. ft.
Set each zone for 133 sq. ft and run some more tests?

Lastly, what impact does the bark over the entire landscape have on evaporation and other advanced settings. Should I change anything?

Thx DD


The actual square footage has a big impact on the estimation.

Seems like your nozzle output might be too high? 1.6/in hr. is typically what you would see from a fixed spray head (our default is 1.5 in/hr.)

2600 sq.ft seems too high for one zone…? Do you what each zone sq. ft. size is?

Good question. My guess is too hard to measure an exact impact. I’d worry more about getting other inputs than the effect of bark on the landscape. :wink:

Hope this helps!



@DD_RioVista_CA, thanks for reaching out. Great questions!

Perfect, this makes scheduling MUCH easier :slight_smile:

Do you know how many emitters you have in each zone?

Correct. 1.6 in/hour is the precip rate for each nozzle, assuming a coverage area of a square foot per nozzle.

Do you have 2600 sq feet of landscaped area? Do you know the linear feet of your drip line? Ideally, you’d enter a square footage equal to the number of emitters per zone, assuming each nozzle outputs coverage of roughly 1 square foot. Since drip emitters are point source emitters, you want to calculated the irrigated area; not the entire surface area of the zone.

Hope this helps!

Best, Emil


Thx Emil! Yes, I guess that is the issue with an all-emitter based system over 2500 sq. ft. They only cover a fraction of the overall sq. ft unlike spray heads. The 2500 sq. ft is only dotted with planting which causes the setup challenge.

I am waiting to talk with the landscaper about where they split Zone 1 & 2. I could then get a better idea of heads per zone. No idea of the linear feet of the larger drip line.

I did a test using the math in my original post (result was to set each zone to 133 sq. ft) and the dashboard then indicated 4 gallons used in the 1 minute test which is pretty close to my manual emitter calc of approx 4.5 Gal. In the dashboard, are the gallons used always rounded to a whole #?

On the weekend I was thinking the same as what you indicated, maybe each emitter would cover 1 sq. ft? That result would be 270 sq. ft combined for both zones (/2 =135 sq. ft per zone which is also very close to my manual calculation.

So, looks like we have a few methods which will give good water-used estimates. Thx for your input!

RE: Advanced Settings: The entire 2500 sq. ft is covered with black bark. Will this have an impact on evaporation, etc., such that I should make any changes to the defaults?

Thx DD


This very long thread talks about how the formula that Rachio provides does not work in your situation (mine is similiar - mostly .5 and 1 GPH emitters, with a few 2GPH emitters tossed in, and no easy way to count them). I ended up running each of my zones for 10 minutes and getting a reading at the meter - defined mine at .2 in/hr and that seems to work well in my case. I would expect yours to be slightly higher since yours are all 1GPH emitters.


I think you will find that this calculator will work much better for you.


@DD_RioVista_CA, this is a common catch 22 of drip zones. Luckily your zones are setup with the same emitters throughout so the numbers are easier to crunch.

Yes, the gallons are always rounded to a whole # in the app.

That’s great that you have a protective layer of mulch to help keep in the moisture! Do you know how thick the mulch is? If it’s over 4" thick, pending your current exposure (sun/shade) setting, you might want to consider increasing the exposure setting as the mulch is effectively shading the soil from evaporation.

@Linn, great idea! Thanks for sharing the drip calculator as well :slight_smile: