Constant Seepage from One Sprinkler Head: Valve or Drainage?

Identifying the Cause of Low-Head Drainage vs. Valve Weeping

Water seeping continuously from a single head in zone 1 when the system is off usually stems from one of two causes: low-head drainage or a weeping valve.

Low-Head Drainage

If the problematic sprinkler is the lowest point in the zone, gravity drains water from the lateral pipes after the valve closes. This is normal but wasteful. Solutions include:

• Installing a check valve under the sprinkler body.
• Replacing the head with a model that has a built-in check valve (e.g., Rain Bird 1800-SAM).

Valve Weeping

If the head isn’t the lowest point, the zone valve may not be sealing completely. Debris, a torn diaphragm, or worn seat can cause slow leakage. To fix:

1. Turn off the water supply.
2. Remove the valve bonnet and inspect the diaphragm for tears or debris.
3. Clean all parts and replace the diaphragm if damaged.
4. Reassemble and test.

Determine which issue you have by observing whether seepage stops after the lateral line fully drains (low-head drainage) or continues indefinitely (valve weep).