City of San Diego Water Department - Landscape Watering Calculator Bubblers Bubblers are used to irrigate individual plants, and are often placed inside watering basins and tree wells.  Installed on rigid plastic pipes 4 to 6 inches above the soil surface, they are ideal for sandy soils where drip irrigation is less effective.  Pressure regulated bubblers deliver a uniform amount of water to each plant, and they require very little maintenance.  The operating pressure ranges from 30 to 50 p.s.i..