Hardie 700 Series Valve Leak: Rebuild vs. Replace

A Hardie 700 series 1½" valve leaking constantly from the lowest head indicates a valve that won't fully close—not low-head drainage (which stops after hours).

Diagnosis Confirmed

Constant wetness = valve seepage. The 1½" size was likely chosen for high-flow zones; replacing with 1" increases friction loss and causes water hammer.

Rebuild First (Cost: ~$50)

1. Shut off main water.
2. Remove valve bonnet (top half).
3. Clean all parts thoroughly—flush debris from body.
4. Inspect diaphragm for tears, warping, or mineral buildup. Replace if any doubt.
5. Check solenoid plunger for smooth action.
6. Reassemble with silicone grease on O-rings.

Hardie 700 bonnet kits (diaphragm, spring, solenoid O-ring) are ~$30–$50. If the body is intact, a rebuild restores function for years.

When to Replace Entire Valve

• Body cracked or threads stripped.
• Seat pitted/eroded (water bypasses diaphragm).
• Multiple rebuilds failed.

If replacing, match 1½" size. Source from irrigation suppliers (Ewing, SiteOne) or online—big-box stores rarely stock 1½".