The DIY sprinkler catch-cup test

Your sprinkler timer measures time, not water. A catch-cup test tells you how many minutes it takes to apply an inch, and whether the spray pattern is even.

You do not need a special kit. Straight-sided cans, a ruler, a timer, and a pen are enough.

What you need

• 6 to 10 straight-sided cans, such as tuna or cat food cans
• A ruler that measures in inches
• A timer
• A pen and paper or your phone
• A sprinkler or irrigation zone

Steps

1. Place the cans in a grid or line. Put some near the sprinkler, some in the middle, and some at the edge of the spray pattern. Penn State suggests one- to two-foot spacing along the throw.
2. Run the zone for a known time. Fifteen minutes is a good starting point.
3. Measure the depth in each can. Write down every number, not just the fullest can.
4. Average the depths. Add them and divide by the number of cans.
5. Calculate minutes per inch. Use this formula:

minutes to apply 1 inch = test minutes ÷ average inches collected

Example: 15 minutes ÷ 0.25 inch = 60 minutes to apply 1 inch.

6. Split the runtime if needed. If 60 minutes is the number, two 30-minute sessions are usually better than one long run, especially on clay or a slope.
7. Check the pattern. If one can has much less water, that area is underwatered. Adjust or replace heads, check pressure, or change the layout. Adding more time to a dry spot can overwater the rest.

Runoff is a signal

If water starts to pool or run off before the cycle ends, stop and let it soak in. Then run the next cycle. This is cycle and soak, and it is more effective than applying the same water all at once.

Record the result

Write down the zone, date, average depth, and minutes. Recheck after changing sprinkler heads, pressure, or the layout. A runtime that was right last year may be wrong now.

Use the number

Plug the result into the watering calculator, then read Watering a Pennsylvania lawn for the rest of the schedule. The goal is a deep soak, not a daily sprinkle.