Apparently this does work, but in hot climates the water will evaporate fairly quickly. What I would want to try is running a hot, long needle through the bottom, in one side and out the other, pulling the thread. That way you could keep the cap on, and probably run the thread along the top of the soil, maybe under a layer of mulch. Maybe it could be done with a gallon jug or larger, and irrigate a large area with a long thread. I'm just spitballing here.

https://youtu.be/0sI_fXUdm18