Measuring how much water your sprinkler system actually applies to your lawn helps you water efficiently, conserve water, and ensure your grass gets the right amount of hydration. This measurement is often referred to as determining your sprinkler system's "precipitation rate."
Why Measure Sprinkler Water Application?
Knowing your system's precipitation rate allows you to:
- Calculate Run Time: Determine exactly how long you need to run your sprinklers to deliver the recommended amount of water (typically 1 inch per week, adjusted for conditions).
- Identify Inconsistencies: Discover areas where sprinklers might not be covering effectively or where coverage is uneven.
- Conserve Water: Avoid overwatering, which wastes water and can harm your lawn.
Step-by-Step Guide to Measuring Sprinkler Rate
The most common and effective method for measuring the water applied by your sprinklers uses simple containers.
- Place Containers: Gather several small containers or cans (like tuna cans or straight-sided jars). Place these containers randomly across your lawn in each watering zone you want to test. Ensure they are placed away from the sprinkler heads themselves to get an accurate measure of the general coverage area.
- Run Sprinklers for 15 Minutes: Turn on your sprinkler system for the specific zone you are testing and let it run for exactly 15 minutes.
- Measure Water Depth: After 15 minutes, turn off the sprinklers. Carefully collect the containers and use a ruler to measure the depth of the water collected in each container. Note these measurements down.
- Calculate Hourly Precipitation Rate: To determine how much water your system applies in a full hour, multiply each measurement by 4 (since 15 minutes is one-quarter of an hour). This gives you the hourly precipitation rate in inches per hour.
Example Measurement & Calculation:
| Container Location | Water Depth (15 min) | Hourly Rate (Depth x 4) |
|---|---|---|
| Area A | 0.20 inches | 0.80 inches/hour |
| Area B | 0.25 inches | 1.00 inches/hour |
| Area C | 0.30 inches | 1.20 inches/hour |
Practical Tips for Accuracy
- Use Multiple Containers: Placing several containers in each zone provides a better average measurement and helps identify areas of uneven coverage.
- Average Measurements: For each zone, average the water depths from all containers before calculating the hourly rate. This gives you a more representative measure for that zone.
- Test Each Zone Separately: If your yard has multiple watering zones controlled by different valves or different types of sprinkler heads, test each zone independently as their precipitation rates can vary significantly.
- Note System Adjustments: If you adjust sprinkler heads during the test, perform the test again to get a new measurement for the adjusted zone.
By following these steps, you can accurately measure your sprinkler system's performance and develop a more effective and efficient watering schedule for your lawn.
