Recurrence changes the diagnosis
A once-off blockage can result from an unusual obstruction. A blockage returning in the same line after proper clearing raises questions about pipe condition, fall, roots, displaced joints, foreign material or how the drain is being used.
Keep a simple history
Record which fixtures are affected, how quickly the blockage returns and what method was previously used to clear it. If possible, note whether the problem follows heavy use or rain. This gives the plumber better evidence than simply reporting that the drain is blocked again.
When inspection is justified
Where the pattern suggests a structural or route problem, camera inspection or other investigation can be more economical than paying for repeated temporary clearing. The inspection should answer a specific question and the findings should be recorded.
Related information
Drain Smells
Drain odours can come from a dry trap, fouling, defective seals, poor venting or a drainage problem further downstream.
When Is a Drain Camera Inspection Worthwhile?
Camera inspection is most useful when the question is why a blockage keeps returning or where a structural defect is located.
Basin Drains Slowly
A slow basin may have a local trap or waste restriction, but recurring symptoms can justify checking the branch drainage and how the fixture is used.
Blocked Drains
A blocked drain is a symptom. The useful question is whether the obstruction is local, recurring or caused by a defect in the drainage system.