Brown Water from Faucets During Sprinkler Run: Source Investigation

Symptom: Brown Water Only When Sprinklers Run

After replacing a faulty backflow preventer, brown water still appears at household faucets during irrigation cycles. This suggests the issue is upstream of the backflow device.

Diagnostic Steps

1. Catch sprinkler water in a bucket: if clear, the irrigation lines are clean.
2. Check meter with all water off: movement indicates a leak between meter and house.
3. Test at the meter: Disconnect house line, run water from meter into a container. If brown, the utility supply is the source.

Common Causes

• Utility main flushing or repairs stirring sediment.
• Galvanized service line corroding (20-year-old poly piping suggests not this).
• High flow from sprinklers scouring pipe walls that low household flow doesn't.

Action

Contact your water utility. If they've done recent work, flushing may continue for weeks. Install a whole-house sediment filter if persistent.