Gardens & grounds / Irrigation
Plan irrigation water use
Add each watering zone, its flow and run time. See the water needed for one run and a week.
Water use plan
How much water?
Enter zones 0 flow litres per minute.
How it works
Put in your numbers
Use your own rates, times and measurements.
See your answer straight away
It works it out as you type.
Copy or print it
Send it on, or keep it with the job.
What it covers: See water per run, week and month from each zone's flow and run time, with an optional cost.
Free to use. No sign-in needed.
How to work out irrigation water use
To see how much water an irrigation system uses, you need the flow rate of each zone and how long it runs. Multiply them for each run, then by the number of runs per week, to get weekly and monthly use. Add your water price to see the monthly cost.
- Choose metres or feet. Add a row for each zone with its measured flow rate, in litres per minute, or US gallons per minute if you chose feet.
- Enter the minutes each zone runs per watering. The calculator multiplies flow by minutes to get the water used by that zone per run.
- It adds the zones together for the water used and the total run time per full run.
- Enter the runs per week, as a whole number, to get weekly use. The average month is weekly use times 52 weeks divided by 12.
- Add your water price per 1,000 litres, or per 1,000 gallons if you chose feet, to see the water cost per month.
Tips and common mistakes
- Find a zone's real flow rate by reading the water meter, running only that zone for a set number of minutes, and reading the meter again.
- Check the units on your water bill. The calculator takes a price per 1,000 litres, which is the same as a price per cubic metre. If your bill uses another unit, convert the price first.
- Revisit run times as the seasons change. Reducing minutes or runs per week in cooler months can save a lot of water.
- Check for leaks or broken sprinklers if usage looks higher than expected.
Questions
How much water does my irrigation system use?
Multiply each zone's flow rate by the minutes it runs, and add the zones together for one run. Multiply by the runs per week for weekly use. Your water meter is the best way to find the real flow rate of each zone.
How do I find the flow rate of a sprinkler zone?
Read your water meter, run one zone for a set time with all other water off, then read it again. Divide the water used by the minutes run to get the flow rate per minute. Repeat for each zone.
How much does it cost to water my garden?
Work out the volume of water used per month, then multiply by the price per unit on your water bill. The calculator does this from a price per 1,000 litres, or per 1,000 gallons in feet, so convert your bill's price to match.
How can I reduce irrigation water use?
Shorten run times or water fewer days a week where plants allow, and adjust for the season. Fix leaks and broken heads, and use drip irrigation for garden beds where it suits. Watering early in the day can reduce losses to evaporation.
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