At half past four on a September morning in Mira Mesa, the mesa is still dark and cool, and the only sounds are a jet spooling up somewhere over Miramar and the faint tick of water meeting soil. That second sound is what drip irrigation is all about: water delivered slowly, right at the roots, before the sun climbs and the day's heat starts pulling moisture back into the sky. Drip Irrigation Systems is named for exactly that craft, setting up and caring for drip lines that feed garden beds, shrubs, trees and the planted ground around a lawn in San Diego. Laid well, a drip line is a small act of respect for every gallon. By the time commuters crowd onto the freeway, the beds have had their drink and the surface is already drying under a clear sky.