Identify where the smell is strongest
Determine whether the odour comes from one basin, shower, floor waste or toilet, or whether several fixtures are affected. Multiple affected points suggest a broader drainage or venting issue.
Check whether the fixture is regularly used
Traps rely on water to block sewer gases. Infrequently used fixtures can lose that water seal. If the smell returns quickly after use, the problem needs further investigation.
Recurring smells need diagnosis
Chemical masking products do not correct failed seals, venting defects or drainage faults. A recurring smell should be treated as a symptom rather than only a cleaning issue.
Related information
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.
Why Does My Drain Keep Blocking?
If a drain blocks repeatedly, the useful next step is to identify why the obstruction keeps returning.
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.