Sprinkler Pressure

Your lawn wants large, thirst-quenching drops of water from your sprinkler. If the sprinklers are creating a mist, most of this water is evaporating and not reaching your plants. Too much pressure can result in misting, fogging and ineffective watering.

Following is some basic advice on how to resolve pressure issues, but as every irrigation system differs, these are only guidelines. A professional plumbing or irrigation specialist may be required.

You will first need to locate your water main. Pictured here is a typical water main / meter stack installation. It is usually located inside your home in the basement or crawl space, nearest the outside wall facing the street. However, some homes have the water meter in a meter pit outside the home. 

Interior Meter Stack
Water_valves

1. Check the shut-off valves

Check your shut off valves to ensure that they are in the fully open position. You could have one of two types of handles :

Lever-type handles should be parallel with your pipe. If your handle is perpendicular or at an angle to the pipe, it indicates the valve is partially or completely closed.

Rounded handle should be opened all the way counter clockwise. If you turn it to the right and it won't move, then it is in the closed position.

2. Check your pressure at an outside hose bib

To check the water pressure, make sure there is no water being used in the house or the irrigation system. A pressure gauge, which you can purchase at a home improvement center for usually less than $15, should be threaded to the hose bib (pictured) like you would a garden hose. Once you have secured the pressure gauge, turn the faucet on all the way. This will give you a baseline of the water pressure at your hose bib. 

Standard pressure should be between 40-80 pounds per square inch (psi). Pressures higher than 80 psi can possibly damage household appliances. Generally, the ideal pressure is 65 psi. A pressure regulating valve (PRV) can be used to reduce if the pressure is higher than 65 psi. 

Pressure_gauge
Pressure Release Valve (PRV)

3. Adjusting a pressure regulating valve (PRV)

Once the household pressure has been determined, you may be able to adjust it up or down using your PRV (pictured). The PRV is normally located in the basement, where your water shut-offs are located. The PRV is a bell shaped fixture with a lock nut and bolt on the end. Using a flat head screwdriver and a wrench, loosen the lock nut by turning it counter clockwise. Do this before adjusting the pressure, which will allow you to maneuver the bolt. Turn the screw clockwise to tighten and increase the pressure, or counter clockwise to loosen and lower the pressure. After each full turn of the screw, take a new reading at your outside faucet. This will ensure you are not adjusting the pressure too high or too low.

Remember to count the turns, in case you want to reset the PRV to its original position. The pressure should not be adjusted above 80 psi. Once you have reached the desired water pressure, make sure you re-tighten the lock nut on the PRV. 

Is your pressure regulating valve failing?

The most common signs that a PRV is failing are:

  • Sudden loss of water pressure and water flow.
  • Sudden high water pressure (which can also be a symptom of a failing water heater expansion tank.)
  • Water pressure surges often occur when a PRV is starting to fail. The water will come out strongly when the faucet is first turned on and then taper off. This means the PRV is unable to hold and maintain the pressure in your system.