How to flush a drain line

Before you start

Confirm that this method matches both the fixture and likely obstruction. Prepare for spills, protect the surrounding surface and keep the work area away from children and pets.

• Controlled water source
• Stopwatch or measured container
• Towels and leak-check access
• Appropriate hot-water limits for the fixture

What a successful result looks like

Normal flow should return without leakage, gurgling or backup elsewhere. If the result is partial or short-lived, stop repeating the same process and investigate farther along the line.

• Stable water level
• Normal drainage speed
• No leak at disturbed joints
• No symptom in a connected fixture

Step-by-step approach

1. 1

   Confirm the line is already flowing

2. 2

   Start with a small controlled volume

3. 3

   Watch every disturbed connection

4. 4

   Increase flow only if drainage remains normal

5. 5

   Stop at the first sign of rise, gurgling or leakage