Create a riddle based on the topic of 'water.'
I'm weightless but you can see me, put me in a bucket and I'll make it lighter, 
I flow like a stream and fall like rain, 
Without me, there is nothing to gain.
What am I?
Complete the following task based on the instruction and optional input provided.### Instruction:
Create a riddle based on the topic of 'water.'

### Output:
I'm weightless but you can see me, put me in a bucket and I'll make it lighter, 
I flow like a stream and fall like rain, 
Without me, there is nothing to gain.
What am I?