# Calibrate zones by measured GPM?

Is there anything in the works to calibrate zones by measuring the water used? On a previous system it was possible to enter the GPM of a zone. This was relatively easy, manually run a zone for one minute and take start/stop readings from one’s water meter. In my opinion, a very accurate method to calibrate zones regardless of sprinkler head type.

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Definitely in our software backlog as to we see a lot of value in this. I don’t know when this is getting built but we want to incorporate it.

@jemanner, until we can support GPM or GPH in the app, you can calculate your PR via your water meter using this equation:

PR = ((96.25(A)/C)

• 96.25 = constant that converts gallons per minute (GPM) to inches per hour. It is derived from 60 minutes per hour divided by 7.48 gallons
per cubic foot. times 12 inches per foot.
• A = gallons from water meter
• C = zone square footage
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Thanks Emil! Once I calculate the Precipitation Rate, this is entered in the Flow Rate with custom nozzles, right? This might take a bit of effort, as with mixed nozzle angles of spray/GPM in a Zone it could require a bit of calculation, such as a 180 degree head would need half a Flow Rate value of a 360, etc. However, it appears doable.

We are a bit away from the watering season here in Rexburg, but getting set up. I’m really enthused about the Rachio, as my prior system did not have the ability to look at weather forecast data, but only ET.

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@jemanner, sorry I missed seeing your reply and questions. But yes you would enter the precip rate (PR) from the inputs above into the flow rate of the custom nozzle in the app.

Since you’re taking the total water applied to the zone from your water meter, it would replace variable A and there’s no need to reduce the output at the head level since it’s recorded at the zone level. A catch cup test would be needed to determine the distribution uniformity of the heads within a zone, which can then tell you which/if any heads need to be replaced.

Hope this helps.

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