Quick answer
A persistent sewage smell indoors means a dry trap, a cracked drain pipe, a failed gully or inspection-eye cover, or a blocked vent pipe. Traps hold a water seal that blocks sewer gas; if a drain is rarely used the water evaporates and the seal is gone. That is the easiest cause to rule out and costs nothing — run water down every drain in the house and wait a day.
Common causes
- Dry trap on a rarely-used drain, guest shower or floor gully
- Cracked drain pipe inside a wall or under the slab venting gas into the structure
- Blocked vent pipe forcing traps to siphon empty when other fixtures discharge
- Failed or missing gully cover or inspection-eye seal outside
- Washing machine or dishwasher waste connected without a proper trap
- Damaged seal at the toilet pan connector letting gas past at floor level
What you can do now
- 1Run water down every drain, including rarely used ones, to refill the traps
- 2Check outside for a displaced gully cover or an open inspection eye
- 3Inspect roof vent pipes for bird nests or debris if you can do so safely
- 4Note where and when the smell is strongest — one room points local, whole-house points at venting
- 5Check whether it worsens after the washing machine discharges, which indicates siphoning
When to call a professional
If the smell persists after refilling every trap and checking the gullies, book a CCTV drain inspection. Sewer gas indoors is a genuine health concern and a persistent smell usually means a cracked pipe or a venting fault that cannot be found without a camera. Call promptly if anyone in the house is getting headaches or nausea.
Typical cost in Johannesburg
CCTV inspection R1,200–R2,400
Indicative ranges only. We provide written, itemised quotes before any work.
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