Drip irrigation systems have come a long way since some ingenious gardener laid pipes, punctured them with small holes and turned water on at low pressure. Some credit drip irrigation to avocado growers, trying to get water to trees on steep California hillsides. Others say the idea originated in Israel. Modern drip irrigation systems can be anything from small plastic emitter devices from which drips emerge to micro-spray systems for flower beds. They also can include flexible porous pipe, that usually is made from recycled car tires and looks similar to a black garden hose.
Water seeps out small openings in the pipe between the particles of recycled tire.
Drip systems usually need a pressure regulation device. If installed without such a device, too much pressure can build up in the system and instead of a slow drip, you may get a stream, although not necessarily a flood. If you're planning to install the system on a hillside, you may need pressure-compensating emitters. You can purchase drip systems as a kit or buy individual fittings. When purchasing individual parts, the manufacturer usually provides instructions about layout design.