How to Calibrate Your Sprinklers

In theory, it is easy to water a lawn, Just turn on sprinkler's system, just leave it on until the water runs down the street and geese begin setting up nests in the grass!

In truth, most people have not got the faintest idea on how long to leave their sprinklers on.

While you may think you're doing fine, you could actually be wasting water by over watering your grass, and slowly killing it by under-watering it . So how long should you leave your sprinklers on? The surest way is to dig small holes or wedges in your lawn as described in this article. If you're not keen on that, though, here's a simple method that can also help you check the functioning of your sprinkler system.


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    Get several shallow cans of equal size. Tuna cans work great for this, but just about any flat-bottomed container with a wide opening will work. The opening of the container should be as large as the bottom (bottles, for example, are not a good choice, because the opening is usually much smaller than the rest of the bottle). All the cans must be of the same size. You don't need more than 3 or 4 cans for each sprinkler head, though the more you have the more accurate your measurements will be.
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    Arrange the cans (open end up) in the lawn around your sprinkler(s). If you just have one sprinkler, set up the cans in various places within the sprinkler's range. If you have an irrigation system (sprinkler system) with multiple sprinkler heads, set up several cans within the range of each sprinkler head, avoiding any areas with overlap (places that get water from two or more sprinkler heads). Try to distribute the cans in such a way as to sample every area the sprinkler waters.
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    Turn on your sprinkler(s) for 15 minutes. If you have a sprinkler system, just turn it on. If you use a hose with a spigot, you want to use the same water pressure that would when you normally water. If you usually just turn the water on full blast, do that. If not, mark a spot on the handle with a marker or a piece of tape or string, and note what position the mark is in when you turn the handle to achieve the desired flow.
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    Measure the water collected in the cans. Once you turn the water off, collect the cans and pour all the water into one container. The container must be exactly the same width as the containers you used to collect the water. Use a ruler to measure how many inches of water are in the can. If you're testing more than one sprinkler, measure each set of cans (the cans around each individual sprinkler) separately from the sets of cans around the other sprinkler heads.
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    Find the average number of inches collected. Divide the total inches measured in the previous step by the number of cans used to collect the water. For example, if you arranged four cans around a sprinkler and collected a total of 2", the average per can is 0.5" (2" / 4 cans). This is the average amount of water distributed onto your lawn in 15 minutes.
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    Figure out how much water your lawn needs. Deep watering is essential to promote healthy, drought-resistant grass. The amount of water your lawn requires depends on the type of grass you have and the type of soil.
    • In general, you should water bluegrass so that the water penetrates 6-8" in the soil; for most other types of grass, you should aim for 8-12".
    • 1" of water applied to the surface will generally permeate sandy soil to 12", loamy soil to 6-8", and clay soil to 4-5".
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    Determine how long to leave your sprinkler(s) on. Use the measurement you obtained to calculate how long you'll need to water according to the guidelines for your grass and soil type. For instance, if your measurements indicate that your sprinkler distributes 0.5" of water in 15 minutes, you will need to leave your sprinkler on for 30 minutes if you have bluegrass and loamy soil, since 30 minutes of watering will give your lawn 1" (2 X 0.5") of water, and 1" of water will penetrate loamy soil to a depth of 6-8", which is exactly the amount required for bluegrass.
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    Ensure adequate, even coverage. If you're checking a sprinkler system and find that one or more sprinkler heads distribute significantly more or less water than the others, you should determine the problem to avoid watering some parts of your lawn more than others. This can happen for a couple reasons.
    • If you have different types of sprinkler heads, you should either change the heads to ensure they're all the same, or zone your sprinkler system so that heads with a greater flow are in a separate zone from those with lesser flows. This way you can turn zones with different flows on and off separately to ensure that each zone is watered only as long as it needs to be.
    • If your sprinkler heads are all the same and you don't have different zones, you may have a problem with your sprinkler system. A broken sprinkler head may be distributing too much or too little water, or an obstruction or leak somewhere in the line could reduce the flow to one or more heads.


  • As you collect the cans from around each sprinkler, take note of any anomalies, such as cans that collected far more or far less water than the other cans around the same sprinkler. This can help you diagnose any problems with your watering coverage.
  • How often should you water? Only when your grass needs it. Check out the related wikiHow article on how to efficiently water your lawn for more information on how to tell when your lawn needs to be watered.
  • If one container won't hold all the water you collected, pour as much water into the container as you can, measure it, and then pour it out and pour more water into it. Add the measurements together and then calculate the average based on this total.
  • This method can also be applied to other plants that you water with a sprinkler. It's important, however, to determine the depth of the root zone for each type of plant. Certain vegetables, for example, can have root zones 4–5 feet (1.2–1.5 m) deep.


  • Newly seeded or sodded lawns require shallower, more frequent spritzing (also called syringing) to keep the top layer of soil damp.
  • Avoid runoff. Some soil types won't be able to quickly absorb the full amount of water required. If you notice water running off your lawn, turn off the sprinklers to allow the water to soak in, and then turn them back on to complete the recommended watering time.

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