A sewer smell keeps coming up through the drains in my flat — what causes it and how do I fix it?

Short answer: a sewer smell from MULTIPLE drains, worse when a bathroom's been unused, is the classic sign of DRY TRAPS. Every drain has a U-shaped trap holding a little water that seals out sewer gas; if a drain isn't used, that water evaporates (fast in the UAE heat) and the seal is gone, so drain gas rises straight into the room. The fix is often as simple as running water into every drain. If it persists with wet traps, it points to a venting problem or a partial blockage — a plumber's call.

What's happening: - Dry P-traps (the #1 cause here): each floor drain, sink and shower has a trap holding a water seal against sewer gas. In an unused bathroom / guest WC / floor drain, that water evaporates (quickly in this climate) and the seal breaks — so gas comes up. The "worse when unused" clue is the giveaway. - Venting problem: drains need a vent so water flows without siphoning the trap seals out. A blocked/poor vent makes traps gurgle and lose their seal even in use. - Partial blockage / build-up in the line growing smelly gunk. - (A dried-out AC condensate trap tied to a drain can do it too — the AC-drain-smell crossover.)

What you can do yourself (try first, it's free): 1. Pour water down every drain — including floor drains and any you never use — to refill the traps. If the smell goes, it was dry traps. 2. For rarely-used drains, top them up periodically (or a little oil on top slows evaporation). 3. Make sure trap caps/covers are in place.

When it's a plumber job: - Smell persists after refilling all traps → likely a venting fault or a blockage/build-up in the line, which needs proper diagnosis (and possibly jetting). - Gurgling drains, or it affects the whole flat consistently.

Common mistake: masking it with air freshener or bleach down one drain — if it's dry traps elsewhere, it just comes back. Refill every trap first; if the smell survives that, get a licensed plumber to check the venting and the line. Anyone's mystery smell turn out to be one forgotten floor drain?