Every gardener wants a simpler way of watering the garden areas. Some gardeners opt for a drip irrigation system which operates through lines run along the property above ground. Other gardeners don't want to see the lines and therefore opt to install underground irrigation pipe instead. Underground systems can be less labor-intensive in the long term, but need more planning, attention to detail and construction during the initial setup of the system.
Water the ground where the irrigation pipes will be laid with the garden hose. This will soften up the soil. Make the ground moist but not soggy. Set the wooden stakes along the path of the irrigation pipe every 12 inches. This ensures you place the lines where you want them.
Using the shovel, dig out a trench 18 inches deep along the path you just laid out, starting at the source of the water. This will keep the irrigation lines below the frost level. Dig the trench for the main irrigation pipe first; then dig the paths for the secondary irrigation pipes out from the main pipeline. Keep the trenches the same depth. Use the shovel to tamp down and level the bottom of the trenches.
Use the hacksaw to cut your pipes to the desired lengths. Install one control valve for each zone you are irrigating. Install the pipe fittings needed and cement the pipes together. Connect any tees, tape or sprinkler heads you need according to the manufacturer's directions. Make sure all of the connections are set before testing the system.
Turn off your water supply from the source. Attach the main valve to the main water line or outdoor faucet. Install the backflow prevention and pressure regulator. Connect the main irrigation line to the water source.
Lay out the pipes assembled in step 3 in the trenches. Ensure that sprinklers are not stuck in position where they become a tripping hazard. Connect the control wiring to the valves. Lay out the wiring along side the irrigation pipe. Leave a 2 inch gap between the wire and the pipe in case of leaks.
Test the system for leaks, pressure, water flow and water distribution by turning on the water and allowing it to run. Back fill the trenches once you are satisfied with the placement and operation of the lines. Check daily for the first week after burying the underground irrigation pipe for leaks. These are found by wet spots along the trenches.