Enrichment · Cultural Studies · Gardening

Too many heads,
too little water.

Time a bucket at the faucet and list the heads. The calculator tells you how many zones the garden needs and how long each should run.

Plan my zonesWhat you get

The garden irrigation zone calculator

The worked example is a front lawn with rotors and sprays and two drip-watered beds. Nothing you type leaves this browser.

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What you get

Enrichment · Cultural StudiesFree

What you finish with
The supply in gallons a minute, the most each zone can draw, the heads’ total flow, the number of zones, gallons a week and minutes a zone a week. It prints as a plan to take to the hardware store.
Who it is for
Home gardeners setting up or fixing a sprinkler system, families planning a new yard, and students running a school garden or agriculture project.
Format
Browser calculator for a phone, tablet or computer, by touch or keyboard. Prints a summary; downloads a spreadsheet (.csv); export and import a file.
Access
Free. No account, no sign-in and nothing to install. Everything you type stays in this browser; nothing is sent to Caveat.
Where it lives
The Cultural Studies space in Caveat Enrichment.
Support
Questions, a correction or a request: team@caveatacademic.com.

How to use it

  1. Time a bucket at the faucet.
  2. List each kind of head.
  3. Copy the flow from the package.
  4. Measure the planted space.
  5. Group like heads into zones.

Plan my zones

How the zones are worked out

Supply flow, a margin, and the heads’ total.

The worked example: a front lawn and vegetable bedsBucket test10 gal/min5 gallons in 30 sA zone may use7.5 gal/min75% of itAll heads25.8 gal/minrotors, sprays, dripZones4 zones43 min each a weekThe worked example: a front lawn and vegetable bedsBucket test10 gal/min5 gallons in 30 sA zone may use7.5 gal/min75% of itAll heads25.8 gal/minrotors, sprays, dripZones4 zones43 min each a week
The faucet’s flow, less a margin, caps each zone; the heads’ total flow divided by that cap is the number of zones.

The bucket test

Open the outdoor faucet fully and time how long a bucket of known size takes to fill. Gallons divided by seconds, times 60, is the flow in gallons a minute. Designers leave a margin, often using about three quarters of it, so the farthest heads still get enough pressure.

Run times

An inch of water over a square foot is 0.623 gallons. Multiply by the planted square feet for a week’s water, and divide by the heads’ flow for the minutes. Rotors and sprays apply water at very different rates, and drip far more slowly, so keep each type on its own zone and adjust by checking the soil.

Sources

  1. U.S. Environmental Protection Agency. WaterSense: watering tips and irrigation system basics (epa.gov/watersense).
  2. U.S. Geological Survey. Water science school: how much water is an inch of rain? (usgs.gov).
  3. U.S. Department of Agriculture, Natural Resources Conservation Service. National Engineering Handbook, irrigation (nrcs.usda.gov).
  4. Cooperative Extension System. Home lawn and garden irrigation guides (extension.org).

A planning estimate; pressure, pipe size and slope change real flows. Follow any local watering rules. Your entries stay in this browser. Support: team@caveatacademic.com.