Dripping Springs Olla The OLLA is buried in the ground with neck exposed and periodically filled with water. The water seeps into the soil at a rate that provides adjacent plants with a constant water source at the roots. Once in place, the OLLAS will typically require refilling a couple times per week depending on soil and weather. Using OLLAS, leaves the soil surface dry resulting in fewer weeds and no soil compaction, a significant drawback of surface watering. Helps conserve water