Water features do not have to be massive in size. One like this usually has a water reserve like a 5 gallon bucket placed under the ground with a recycle pump. The rocks cover the reservoir and allow the water to flow back to the pump.
In a Garden in Yorkshire - "An ancient stone trough, with a lion-shaped spout, turns a rustic garden wall into an unusual water feature. Box, erigeron and bamboo edge the area, giving it a magical appearance"