Average Flow Rate for Drip Zones?


Hello! There’s probably no simple answer to this question, but I’m wondering what the average flow rate for a spray zone with 6-8 heads might be. We just got a pretty jaw-dropping water bill (the first after installing the irrigation system), and I’m trying to figure out whether there’s a leak somewhere or watering the lawn is just that expensive. I just installed the flow meter and got calibration readings between 2.9 GPM (the smallest zone with only 4 heads) and 6.3 GPM (largest zone with 9 heads). Pardon me if I’m missing a bunch of necessary information as I ask this question, and thanks a ton for your help!


@WBanks - correct on multiple accounts - no simple answer and tons of missing information.

If you have access to the water meter, go look and see if the smallest wheel is turning when no water should be running.

What was the difference in gallons between the two bills? Cost of water? etc.


Typical flow rates on standard spray nozzles can range from .18 Gallons per minute up to 2.7 gallons per minute. This all depend on the valve size and total pressure for the line.

Drip lines are no longer in GPM or Gallons Per Minute and rated in GPH or Gallons Per Hour. A single drip emitter, on a 30PSI line, will deliver 1/2 GPH up to 8GPH depending on the rated emitter that you install.

Most companies will have a color coding to determine the GPH rating and the color coding will vary from one manufacturer to another.

The flow rate can be calculated by the number of emitters in a given line.

Count the number of emitters on your line. Ie: 100 emitters at 2GPH will be 200 gallons per hour. Divide by 60 to get your Gallons per minute equivalent

Watering you lawn can take up to 3 times the amount of water compared to plants. This is based on using fixed spray heads.

While I never recommend using drip on lawns, some people do it anyways. There is no real savings to watering lawn on drip since you need to saturate 100% of the soil anyways. The only advantage is that you can water a lawn on drip during a wind storm without losing most of your water to the wind…


@WBanks I’ve got a customer with a small dripped bed. The average flow is 1.5 GPM through the flow sensor. Drip lines range from .4GPH to .9GPH. The sensor will show you GPM, though, not GPH. The spray zones on this property range from 8GPM to 21GPM.

Watering your lawn can be expensive and most end users underestimate how much water an irrigation system actually uses. Although, most on this forum are very in tune with how their irrigation works now.

Was there a master valve installed on your irrigation system?


@DLane Thanks a ton for your response! Unfortunately my water meter is this little digital thing-- no wheels, just an LCD display that doesn’t seem to indicate flow irregularities in any way.

Our bills come every two months, and our previous bill had us at 17,204 gal from 6/14/18 to 8/14/18. Our water utility charges are tiered by “units”. 1 unit = 748 gal. First 8 units are $5.91 each, next 12 units are $7.09 each, then the third tier is $9.83/unit. Total for this previous bill was $242.29.

Our current bill for 8/14/18 - 10/14/18. I am noticing now that water rates seem to have increased since the last bill, so there’s one factor right there. We also reached the fourth tier this billing cycle. On the current bill we used 35,156 gal for a total of $517.95.

@spscoutenPhD Thanks a ton for the info! I looked back at my design data and fixture specs and it looks like everything is functioning as intended.

@Sprinklerman I did install a master (ball) valve on the system. Thanks so much for your response!

Additional stuff: I’ve done a visual inspection of everywhere I laid the mainline and laterals for the system, as well as a check of all sprayheads while the zones were running to check for any loose fixtures or blown fittings, haven’t turned up any problems there.

Hey thanks again everyone for giving me a hand getting to the bottom of this!