The amount it does can help check your irrigation system’s efficiency and prevent water waste.
Not surprisingly, sprinkler systems are designed to replicate the effect of natural rainfall with precipitation rate as the measure of how much water is delivered to an area over time (typically expressed in inches per hour).
By managing the precipitation rates of our sprinkler systems and ensuring they’re matched within each sprinkler zone, we can optimize irrigation efficiency and prevent water waste.
An essential principle in irrigation design, matched precipitation ensures each sprinkler head within a single zone applies water at the same rate. This uniformity helps achieve even distribution of water, prevents overwatering and minimizes water waste. Without matched precipitation, some areas may get too much water while others are underwatered, leading to stressed plants and increased water costs.
Different sprinkler components, such as spray heads and rotor heads, can apply water at vastly different precipitation rates, and this can disrupt irrigation efficiency if they’re used together within the same zone.
A practical way to measure the efficiency and uniformity of your sprinkler zones is with a catch can test. This allows you to evaluate the distribution of water and understand how to adjust your system for balanced watering.
Here’s how to conduct a catch can test:
- Gather materials. You’ll need 10-20 identical catch cans or containers (recycled tunafish cans are a popular choice, but commercial catch can sets are available too), a ruler and a stopwatch.
- Arrange the cans. Place them evenly throughout the sprinkler zone. Ensure coverage across the entire area, including both the edges and the center.
- Run the system. Turn on the sprinklers for a set period, about 10 minutes.
- Measure the water. Use a ruler to measure the amount of water in each can and record the readings. These measurements can be averaged to determine zone precipitation rate and help with scheduling run times.
- Calculate and compare the water collected in each can. Ideally, measurements will be consistent across the zone. Variations indicate poor distribution, which can often be improved by adjusting sprinkler spacing or nozzle selection.
With these measurements, you can determine the average precipitation rate for each zone.
By ensuring each zone consists of heads and nozzles that produce a matched precipitation rate, you can better control water application rates to match each area’s needs. Set the irrigation schedule according to the precipitation rate for each type of head to avoid overwatering.
Regular catch can testing and adjustments are essential to maintain irrigation system efficiency, support healthy plant growth and conserve water.
