What could I do with the rainwater I collected?

You could keep a small, labeled jar as a reminder of the storm and use it in a quiet intention-setting ritual. The meaning can be personal, so there’s no need to follow a particular tradition.

For something simple and practical, use a little to water an outdoor plant while focusing on what you’d like to nurture or let go of. I’d skip drinking it or putting it on your skin, since collected water can pick up contaminants.

If you want to save it for later, strain out visible bits and store it in a clean, closed container. You could reserve a small amount for symbolic use and let the rest go to the garden. No need to make the whole supply into a project.