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how to Tap Into The Main Water Supply Line

To supply a new sprinkler system, you’ll have to tap into your existing cold-water supply system. If your plan calls for cutting existing pipes, you may prefer to hire a plumber. If you do decided to tackle it yourself, be sure to turn off the water supply before you begin any work.


In mild climates, you may tap into an outdoor faucet. In cold-winter climates, or if you don’t have adequate water flow at the faucet, you can cut into your main supply line.

Cutting in at an Existing Faucet
Often the easiest course of action is to make the connection at the pipe serving the faucet. With this method, you avoid cutting pipe. Turn off the house water supply and drain the faucet, then remove the faucet and install a brass or galvanized tee. Match the outlet sizes to the faucet pipe and the irrigation pipe you plan to use. Reattach the faucet; then install a nipple (a short length of pipe threaded at each end) in the stem of the tee fitting and connect a shutoff valve to that.

Cutting in at the Service Line

By cutting into your service line and slipping on a compression tee, you can connect your sprinkler system to the water supply without soldering. In some instances, you can avoid cutting the main line by attaching your system to the outside faucet connection (see diagram and note). PVC pipe may be substituted for copper in non-freezing areas.

Whether a PVB is used or not, we recommend installing a shut-off valve between the zone valves and the service line. This will allow you to easily turn off the water to your irrigation system if you need to make repairs or replace parts. Check local codes for the type of shut-off valve recommended.

NOTE:  Pipes should be buried at least 6 inches under the ground.

** To activate the flow of water, click the "blue" water button on the top right of the image.


  1. Shut off your water supply at the meter
    (check with your water department first).
  2. Dig to expose the service line.
  3. Tie into the service line, between
    the water meter and the house.
  4. Remove a section of pipe, leaving a gap
    large enough to slide on a compression tee.
  5. Slip the tee over each end of the pipe.
  6. Tighten the compression nuts. The rubber gasket will compress against the pipe, creating a seal to prevent leakage.
  7. Install a short nipple, using PTFE tape on all threaded connections to the tee.
  8. Attach a shut-off valve, in a small enclosure, to this section of pipe. The shut-off valve allows you to turn off the system by hand, if necessary.
  9. keep this connection as clean as possible.
    This is your tap water supply.

** To activate the flow of water, click the "blue" water button on the top right of the image.


  1. Shut off your water supply at the meter
    (check with your water utility).
  2. Install an appropriate tee into the service line for the irrigation connection.
  3. Drill a hole through the sill above the foundation, or chisel a hole in the basement wall for the irrigation line to run through. Make it no bigger than needed for a 1" pipe.
  4. Install the connection fittings, as shown. A full-flow ball valve is a good choice for the irrigation shut-off so that you can service your system without having to shut down the entire household's water supply.
  5. A reduced pressure backflow preventer, designed for below-grade, should be connected next along the pipe, followed by a drain valve. For the drain valve, use a gate-type valve. The drain valve should be as low as possible to allow complete system drainage.
  6. Finally, seal the hole in the sill or foundation with caulking compound.

** To activate the flow of water, click the "blue" water button on the top of the image.


Whenever you attach to a potable water system (like your indoor plumbing), always install a backflow preventer to prevent used water from flowing back into the water supply.  If you are using antisiphon control valves, a preventer is built into each valve. For a single-circuit system that runs directly off the hose bibb, you can screw a vacuum breaker onto the end of the faucet. Inline valves need a pressure vacuum breaker at the start of the system, as long as it is located higher than the highest sprinkler head. Otherwise, you’ll need to install a reduced-pressure (RP) principle backflow preventer on the main line before the valves at a point at least 12 inches above ground.

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Reduced Pressure Principle Backflow Preventer

Vacuum Breaker

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