Water Leaking from Sprinkler Heads
When your irrigation system is off but water still flows from a sprinkler head
Water leaking from a sprinkler head when the system is off is usually caused by one of these issues:
Low Head Drainage
When your irrigation system shuts off, water that's trapped in the pipes naturally drains to the lowest point in the zone due to gravity. Sprinkler heads at the bottom of a slope or in low-lying areas will "weep" or gush water for several minutes after the system turns off.
Why it happens:
- The pipes are full of pressurized water during operation
- When the valve closes, that water has nowhere to go
- Gravity pulls it downward through the pipes
- The lowest sprinkler heads release it
Signs this is the problem:
- Only affects the lowest heads in a zone
- Happens every time the system shuts off
- Creates puddles or soggy spots
- May cause erosion around the head
Solutions
- Install check valves (also called anti-drain valves) in the sprinkler heads or on the lateral lines
- Use sprinkler heads with built-in check valves
- Install spring-loaded check valves at low points in the system
Damaged Wiper Seal or Internal Seal
If the wiper seal or other internal seals are worn, cracked, or damaged, water can leak past them even when the system is off and there's residual pressure in the lines.
Signs this is the problem:
- Leak continues for an extended period (more than 5-10 minutes)
- Water seeps from around the shaft or base
- May also leak during operation
Solutions
- Disassemble and replace the seal
- If the entire mechanism is worn, replace the sprinkler head
Valve Not Closing Completely
A faulty zone valve (the valve that controls water flow to that irrigation zone) may not be shutting off completely, allowing water to continue flowing at low pressure.
Signs this is the problem:
- Multiple heads in the same zone leak continuously
- Leak doesn't stop after a few minutes
- You hear water running in the valve box
- Water meter shows continued usage when system should be off
Causes:
- Dirt or debris stuck in the valve diaphragm
- Torn or damaged diaphragm
- Faulty solenoid
- Damaged valve seat
Solutions
- Clean or replace the valve diaphragm
- Replace the solenoid if electrical
- Rebuild or replace the entire valve if damaged
Cracked Sprinkler Body or Fittings
Physical damage to the sprinkler body, riser, or pipe fittings can cause leaks regardless of whether the system is running.
Signs this is the problem:
- Constant leak that doesn't vary with system operation
- Visible cracks in the plastic body
- Water bubbling up from underground (broken pipe or fitting)
Solutions
- Replace the damaged sprinkler head or fitting
- Repair or replace cracked pipes
How to Diagnose
- Observe the pattern – Does it stop after a few minutes (low head drainage) or continue indefinitely (valve/seal problem)?
- Check multiple heads – Is it just the lowest ones (drainage) or several in the zone (valve issue)?
- Inspect the head – Look for visible cracks or damage
- Listen at the valve box – Can you hear water flowing when the system should be off?