Common Symptoms

  • Zone won't turn off: Water continues flowing even with controller off
  • Constant dripping from heads: Low-pressure water seeps through closed valve
  • Water around valve box: External leak from valve body or fittings
  • Zone runs weak: Debris in diaphragm preventing full opening

Tools Needed

  • Flat-blade screwdriver
  • Adjustable wrench or pliers
  • Small bucket or towels
  • Wire brush (for cleaning)

Supplies from Lowe's

Before You Start

Turn off water to the irrigation system at the main shut-off valve or backflow preventer. Release pressure by briefly turning on the zone at the controller.

Locating valve box

1 Locate and Access the Valve

Find the valve box for the affected zone. Usually located near the water source or along the edge of the lawn. Remove the lid and clear debris from around the valve.

If water is pooled in the box, bail it out to see what you're working with.

Removing valve bonnet

2 Remove the Bonnet (Top)

  1. Unscrew the solenoid (black cylinder on top) by turning counter-clockwise
  2. Remove the screws holding the bonnet/lid to the valve body
  3. Carefully lift off the bonnet - the diaphragm may come with it
  4. Note the orientation of all parts for reassembly
Valve diaphragm inspection

3 Inspect and Replace the Diaphragm

The diaphragm is a rubber disc that seals the valve. Look for:

  • Tears, holes, or cracks in the rubber
  • Debris or grit on the sealing surfaces
  • Warping or deformation
  • Mineral buildup

Replace if damaged, or clean thoroughly if just dirty. Install new diaphragm with the same orientation as the old one.

Pro Tip

Take a photo of the diaphragm position before removing. Different valve brands have specific orientations.

Shop Valve Parts at Lowe's

Find diaphragm kits, solenoids, and complete valves from Rain Bird, Orbit, and Hunter.

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Solenoid replacement

4 Check the Solenoid

If the diaphragm looks good but the valve still malfunctions:

  • Test the solenoid with a multimeter (should read 20-60 ohms)
  • Check for cracked housing or damaged plunger
  • Replace if resistance is infinite (open circuit) or near zero (short)

Solenoids are specific to valve brands - match your existing one or bring it to Lowe's.

5 Reassemble and Test

  1. Place the diaphragm back in position
  2. Align the bonnet and tighten screws evenly (don't overtighten)
  3. Screw the solenoid back on hand-tight
  4. Turn water back on slowly
  5. Run the zone and check for leaks

Still Leaking?

If the valve still leaks after replacing the diaphragm and solenoid, the valve body may be cracked or corroded. Replace the entire valve assembly.

When to Replace the Entire Valve

  • Cracked valve body
  • Severe corrosion on ports
  • Repeated failures after diaphragm replacement
  • Valve is 15+ years old
  • Can't find matching replacement parts

Full valve replacement requires cutting and gluing PVC. See our pipe repair guide for gluing techniques.

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