- Measure the diameter of the larger container. Put the container out in the rain on a level surface. Move to step 2 when rain has completed.
- Measure the diameter of the small cylindrical container. It must be a cylinder, straight edges with a circular opening. The collected rain will be transferred here.
- Transfer water from larger container to smaller container. This may require several transfers.
Record height of water transferred each time then add them all up when complete.
- Enter total height of water collected into smaller container using inches.