Smell after plumbing repair

Quick Answer:

If you notice a new sewer‑like or chemical smell right after a plumbing repair, recheck the work area for loose fittings, run the fixture while sniffing joints, and inspect nearby traps and floor drains. Often the issue is a loose trap adapter, a disturbed floor drain, or a venting disconnect that was missed. If the smell persists or you see water where it shouldn’t be, call the technician or a licensed plumber.

Why This Happens

Repairs can disturb seals, traps, or vent connections. A trap that is not seated, a slip nut left loose, or an open trap adapter lets sewer gas escape. Rerouting or replacing piping can also create an accidental disconnect in the vent path, allowing odors to travel back into the room. Work near floor drains can knock traps dry or break seals. Sometimes the smell is from cleaning residues or adhesives used during repair, but it’s best to verify there are no gas pathways from the drain system.

Step-by-Step What to Do

Step 1 — Recheck the repaired fixture area

Look closely at the repair site for any visibly loose fittings, gaps, or an open trap adapter where the trap meets the tailpiece or drain. A small gap can let sewer gas escape.
Feel for wetness around joints that might mean a leak is sending odors out as water evaporates.

Step 2 — Run the fixture while sniffing joints

Turn the repaired fixture on and run water for a minute. While it runs, move your nose slowly along the pipe joints, trap, and connections to locate the source of the odor.
Listen for hissing or bubbling sounds that could indicate a leak in a pressurized or vented section.

Step 3 — Inspect nearby floor drains and traps

Check floor drains, shower drains, and other traps near the repair; they may have been disturbed or partially dried during work.
Pour a small amount of water into dry traps to reseal them, then watch for returning odors.

Step 4 — Tighten accessible slip nuts and retest

Carefully hand‑tighten accessible slip nuts on trap assemblies and drain connections—do not force fittings that require tools or advanced steps.
Retest by running the fixture again and sniffing joints to see if the odor stops.

Step 5 — If rerouting was involved, review the new venting path

If the repair included rerouting pipes, visually follow the new venting route where you can. Look for accidental disconnects, missing vent connectors, or improperly sloped sections that could trap odors.
If you cannot confidently inspect the vents, ask the technician to explain or verify the vent work they performed.

What Not to Do

Avoid undoing complex repairs yourself or pouring chemicals to ‘fix’ the smell—this can hide leaks; call a pro when you detect persistent odors immediately after a repair or see water pooling around joints.
Do not ignore the smell or assume it will go away without checking traps and connections.

When to Call a Professional

Call the technician who did the repair if the smell appears immediately afterward. They should return to inspect and correct any mistakes.
Contact a licensed plumber if you still detect odors after doing the basic checks, if you find wetness where there shouldn’t be any, or if you suspect a vent disconnect or broken sewer line.
If you smell gas (natural gas or propane) rather than sewer odor, evacuate and call the gas company or emergency services right away—do not attempt to locate a gas leak yourself.

Safety Notes

Work with good ventilation when inspecting odors; open windows and doors if safe to do so.
Use gloves when checking under sinks or handling traps; some residues can be contaminated.
If you must tighten fittings, use the correct wrench and avoid over‑tightening plastic fittings which can crack.
If you are unsure about any step, stop and call a licensed plumber—incorrect fixes can make problems worse.

Common Homeowner Questions

Why did the smell start only after the repair? Because the repair likely disturbed a seal, trap, or vent connection that previously blocked sewer gas.
Can I fix it myself if I find a loose slip nut? You can gently tighten accessible slip nuts by hand or with a proper wrench, but avoid forcing parts you don’t understand—call the technician if unsure.
Should I be worried about mold or other hazards? Persistent moisture from leaks can lead to mold; if you find pooling water or repeated leaks, have a professional assess both the leak and any resulting damage.

If you recently had other work done in the house and notice odors in different rooms, consider checking related pages about Smell after remodel and Smell after drain cleaning for common causes and next steps.