I made this few days ago. This is the video of it. The water go with the string.
Making this is very easy(more than the one with airpumps).
1. Hang some bottles on the window.(1 bottles to store water(top), others for plants.)
2. Connect the bottles of plants and the top bottle with strings.
3. Put a bucket on the bottom.
4.the end (But when the water is all fallen, pour the water on the bottom one into the top one with your hand.)