Parental supervision may be necessary for younger children when cutting the bottle.

Make sure that the top half is firmly held in place, and that there aren’t any gaps between the two pieces of your gauge.

Use duct tape for it’s strong adhesive properties. Masking tape, or other forms of tape, may come loose when soaking wet.

Every half interval does not need to be labeled. Label every other mark by beginning with the second mark as 1 inch or cm. The marks in-between each label are a half measurement. Make sure to wait until your marker dries on the tape before placing your gauge in the rain. Do not use washable markers or apply markings while in the rain. If you have to reapply new tape or new markings midway through the experiment, your results may be considered inaccurate. You may use any unit of measurement your experiment calls for. You can mark off every quarter-inch, eighth-inch, or centimeter.

You may also use coloured jelly instead of water to give yourself a reference point of where to start measuring. Use jelly or oil rather than another liquid as those may dissolve and mix into the water, ruining your measurements. These bottles are not evenly shaped on the bottom so you must account for this by establishing your starting point. Make sure that the gauge is in a protected area. You want to ensure that there’s no disturbance from wind, debris, or anything else that could block or prevent rain from entering, like a branch or powerline.

Check how closely your measurements compare to official ones by checking the news or online for the rainfall measurements of your area for the day.

Try to take your measurements at roughly the same time so that you get a 24-hour reading. Then, dump the rain out between each measurement to start a new measurement for the next day.

Keep it upright by placing it in a bucket or container. You may also dig a hole for the gauge to stand about halfway in.

For example, your measuring cylinder may be measuring in cm so if you have collected rain for one week and the water you pour in from your rain gauge reaches the 10 cm mark on your measuring cylinder, you can ascertain that roughly 10 cm of rain has fallen during the week. Compare your daily measurements. Using a pen and paper, record your findings every day at the exact same time of day to give you an accurate comparison.

You may also compare your findings with the wind speed, wind direction, or air pressure. Be sure to always replace your gauge at the same location.