You are here: Home / Irrigation

ThinkWater

Simple Irrigation Audit

Are you overwatering?

A simple irrigation audit can be used to measure the output and uniformity of your irrigation system. This procedure may save you money and can help conserve water.  For more information about a simple irrigation audit check out Extension factsheet HLA-6610 or L-434

See video below for demonstration!

Setup

  1. Find nine irrigation catch cups that have measurement markings

Option 1: Purchase small rain gauges and place them in your yard at 2-3 inches above the soil.

Option 2: Make your own. Measuring cups can be easily made from tuna or cat food cans. Clean and remove the labels and mark measurements with a permanent marker. Using a ruler, mark the outside at 0.1 inch, 0.2 inch and so on to the 1-inch mark from the bottom of the can.

Option 3: Pre-marked irrigation catch cups can be purchased from various professional irrigation suppliers' websites

  1. Find a relatively flat area that is approximately 16 feet x 16 feet. Starting at the edge of the perimeter, place one catch cup, then measure approximately 8 feet, and place another cup in a grid pattern.
  2. Set up a sprinkler along one side of the grid where you will get good coverage for each side. Turn on sprinklers to adjust spray pat­tern before setting timer. Pour out any water accumulated in the cups while setting up sprinklers.

Watering the Grid

  1. Turn on your sprinkler and let it run for 20 minutes.
  2. After watering the first side, move you sprinkler to the other side along the relative midpoint, and water the grid for an additional 20 minutes.
  3. If you are working with an oscillating sprinkler or automatic system, you will finish with the first timing.
  4. After 20 minutes, turn off irrigation and check your catch cups.
  5. If there is not a measurable amount in five out of the nine cups, you will need to water for one hour.

Irrigation Output and Uniformity Measurements

  1. Gather your cups and pour the water from the eight catch cups into the ninth one.
  2. The cumulative amount will be the sum of all nine collection points.
  3. To obtain uniformity data, you can measure each of the nine cups separately and record the exact amount collected in each cup.
  4. This data will give you an idea of how uniform your sprinklers or automatic system covers an area of your yard.

Measuring the Results

  1. Take the total of the catch cups’ measurement and divide by nine to find the average amount of output.
  2. If you watered for 20 minutes, you will need to multiply the average amount you found by 3 to get the output per hour.
  3. If you watered with sprinklers on each side for 20 minutes, you still multiply by 3 as this set up was for obtain­ing even coverage.
  4. Total water collected in 20 minutes / 9 = average water collected in 20 minutes; and average water collected in 20 minutes x 3 = irrigation output in inches per hour.

Interpretation

Many homeowners find that they have been over­watering their turfgrass. If you are watering your lawn for 30 minutes per session, and your output was only 0.2 inch/hour, that 30 minute session would only be delivering one-tenth inch of irrigation. If your output number were larger, say .6 inch per hour, and your sprinkler system was set for 1 hour every day, this would apply 4.2 inches of irrigation per week, which is about four times more than what an established bermudagrass yard actually needs.