How to Make a Rain Gauge

Build your own rain gauge to measure rainfall in your backyard using simple materials.

1. Prepare your bottle. Ask a grown-up to help you cut the plastic bottle about 1/3 from the top. You'll have a bottom part (your gauge) and a top part (your funnel). Remove any labels and wash both pieces clean.
2. Add weight to the bottom. Put a handful of small rocks or marbles in the bottom of your bottle. This will keep your rain gauge from tipping over in the wind. The rocks should cover the bottom but not fill more than 1 inch.
3. Create your measuring scale. Stick a piece of masking tape vertically on the outside of your bottle, starting just above the rocks. Use your ruler and permanent marker to make small marks every 1/4 inch on the tape. Number every inch: 1, 2, 3, and so on.
4. Make the funnel top. Take the top piece of your bottle and flip it upside down so the narrow opening points down into the bottom piece. This creates a funnel that will catch rainwater and direct it into your gauge.
5. Set up your gauge. Place your rain gauge outside in an open area away from trees, buildings, or overhangs. The funnel should be level and stable. You want rain to fall directly into it without anything blocking or splashing extra water in.
6. Start measuring. After it rains, check your gauge and read the water level on your scale. Write down the measurement, then pour out the water to reset for the next rainfall. Keep a weather journal to track your measurements!