Once installed below the ground level, or just under mulch, a drip watering system is hidden from view. People naturally think that gravity will cause the water to flow down even deeper. Actually some does go down, but it also goes upward and outward due to capillary action between the dirt particles. Drip watering systems are simple for the homeowner to install. Wherever it passes a plant that needs water, you attach a tiny emitter to the tubing.
Emitters are available in various water flow rates and many cost less than a dollar.
Using a simple punch that all the manufacturers offer, punch tiny holes in the wall of the tubing. The tiny emitters are designed with a special end to snap and seal into the hole. Place them on the top side. They are sold as complete kits often with an automatic fertilizer accessories available. Most emitters are color-coded to indicate the water flow rate from them.