Water application measurement

Having good equipment is one thing; making it work correctly is quite another. Check out how well the irrigation system delivers water. The goal is the same as for fertilizer--every part of the lawn should receive the exact same amount.

It's easy to determine how uniform the application of water is. Follow the steps given below and illustrated in the animation "Inspecting your Sprinkler System".

1. Turn on the sprinklers and place a flag by each head. You can do this step without operating the system, but sometimes it's hard to locate the heads.
2. Turn it off and place small collection devices in the lawn to measure output. Tuna cans work quite well--collect about 10 (this might be the hardest task, depending on how much you like tuna; Personally, I'd rather starve than eat tuna fish; however, tuna steak in a nice seafood restaurant is great).
3. You can place them just about anywhere in the lawn, but be sure to place one can about 2 feet away from a head or sprinkler device.
4. If you have an automatic system, place a can between the heads as well.
5. Turn the sprinklers back on and let the system run for 15 minutes. This is sufficient time to observe inefficiencies and to calculate a rate of output per hour.
6. Walk out on the lawn and measure the amount in each can (you'll want to be wearing rubber boots or old tennis shoes).
7. Use a ruler with a metric (mm) scale for the best comparisons between cans.
8. Mark each can location and amount collected on a simple sketch of the lawn.
9. Compare the amounts. If they vary more than 20%, adjustments should be made.

Many possibilities exist for differences in amounts collected.

• Tree roots growing around supply lines;
• wind gusts that distort the pattern;
• misaligned heads that spray water into the street;
• heads that don't turn as they should, heads that don't rise up far enough out of the lawn;
• trees or shrubs that obstruct the pattern;
• internal parts of spray heads that are broken, leaking or worn.

There's just a lot that can go wrong. Replace any parts of the system that turn out to be responsible for inefficiency. Sprinkler systems are mechanical just like your car; they're made with parts that will eventually fail.

Sprinklers apply about twice as much water near the head as at the end of the water delivery pattern. Automatic systems are designed to allow for this, with the heads spraying towards each other, so that the lesser amounts applied by one head will be made up for by a nearby head. Devices that attach to a hose can be adjusted to deliver the same amount over the whole lawn. The most common way to accomplish this is to rotate the sprinkler to a different part of the lawn each time you water.

Measuring the output from drip and soaker hoses commonly used in veggie gardens and ornamental beds is much the same as for lawns.

1. Set a collection device under the water emitter and run the system.
2. Repeat for various parts of the system, comparing the output.
3. Again, if more than a 20% difference exists between collection points, then a problem exists. Replace parts as needed to increase irrigation efficiency.

Information presented within the Lawn & Landscape Irrigation section of this Water Web site has been reviewed by University of Nebraska - Lincoln Educator John Fech.