Gardening Tips: How To Install an Underground Sprinkler System

An underground sprinkler system can be a real time saver for homeowners who wish to maintain a beautiful lawn. Designing and installing the system is more complicated than dragging out the old garden hose and sprinkler, but the benefits of such systems last a long time afterward.

Pieces Parts

An underground system can be either manually or automatically activated. With a manual system, you turn on the sprinklers by opening a water valve by hand each time you want to water. Automatic systems use a timer. Both systems are installed basically the same way. The valve is usually located directly outside the house, and can be connected to an existing outdoor faucet.

Eighty percent of all systems are installed using PVC. Polyethylene plastic pipes are also used because plastic is easier to work with than metal, less expensive, and less likely to crack during a winter freeze. PVC is a rigid plastic and is the stronger of the two. It should always be used at the main water supply to the sprinkler system. Polyethylene is flexible, and can be curved around trees, shrubs and other obstacles, using fewer fittings than PVC. They’re held in place with metal clamps. Both types of pipe are cut with a hand saw or cutter.

How To Install an Underground Sprinkler System

Some Planning Tips

  • Before you begin, design your sprinkler system plan on paper. Drawing a diagram of your yard is crucial to success. This will provide a basic “grid” on which to locate trees, outbuildings and other obstacles. A survey plot plan of your property is helpful for this. It is much easier to explore alternatives on paper before you begin digging.
  • Check local building and water authority codes. Consult your county extension agent for the recommended frequency of watering in your neighborhood.
  • Check water pressure in your home.
  • Consult the dealer about the type of system to fit your needs.
  • Lowe’s offers a free (about $150 elsewhere) computer-design service plus an in-store planning guide. Just diagram your layout. Bring it to a Lowe’s store near you and we will design your system for you in about 7-10 days.

Installing Your Sprinkler System

  1. Lay out the sprinkler system above ground. Before digging, find out if any underground pipes or wires are in your path. Most cities and suburban communities have a service that keeps track of underground pipes and wires; some localities require you to call your power company for this information.
  2. Check the watering coverage of the system and make necessary adjustments. The sprinkler heads should be positioned so the outer edges of the spray area, which receive the least amount of water, overlap wherever possible. This ensures a even watering.
  3. Place stakes and strings at the locations of the heads and pipes, respectively. PVC pipes are connected with special solvent cement which stays wet for several minutes once applied, but bonds in seconds once the pieces are put together. When gluing PVC, first wipe the pipe and fitting with PVC pipe cleaner, then swab the inside of the fitting and the outside of the pipe with cement. Insert the pipe into the fitting and give it a quarter turn to distribute the solvent evenly.
  4. Remove sod and dirt along the marked locations, and dig holes and trenches for the sprinkler heads and pipes. Using a trencher (you can rent one) is an alternative to manually digging a trench for the system pipe. A trencher speeds up the job considerably, particularly if you keep the ground well watered for a week before digging.
  5. Install pipes and sprinkler heads.
  6. Replace dirt and sod.

A Final Note
Sprinkler heads are installed just below ground level. The best ones are adjustable. A dampness meter, combined with a digital controller, shuts the water off when the soil has reached a preset moistness. When the ground dries out, the meter sends a signal to the controller. The system keeps the lawn well watered whether you are home or not.

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