Quick Answer:
If you smell a stale or musty odor at the sink after winterizing or de-winterizing, the first and simplest fix is to run water to refill the P-trap and flush any antifreeze or stagnant water out of the lines. Check other, unused fixtures too so smells don’t migrate. If those steps don’t clear the smell and it spreads, call a plumber.
Why This Happens
When you winterize, you either drain water from the lines or add antifreeze to prevent freeze damage. A dry P-trap or leftover antifreeze and stagnant water can let sewer or chemical smells into the room. Odors can also come from nearby fixtures, a garbage disposal, or trapped food. If the disposal or sink was used after de-winterizing, you might see other symptom patterns such as Disposal smells metallic or Odor worsens after grinding fibrous foods—those are separate issues but can be mistaken for a trap problem.
Step-by-Step What to Do
1. Run water to refill the P-trap
- Turn on the cold and hot water and let it run for at least 30–60 seconds. That refills the P-trap so the water seal blocks sewer gases.
- If the sink hasn’t been used for a long period, run for a minute or two to be sure the trap is full.
2. Flush if winterization involved antifreeze or drained lines
- Run a steady stream of water for several minutes to flush antifreeze or stagnant water out of the drain and trap. Repeat with both cold and warm water.
- Ventilate the area while flushing so any chemical odor dissipates.
3. Check other fixtures and traps
- Open and run water in nearby or unused sinks, showers, and floor drains to ensure their traps are filled. A dry trap on any nearby fixture can allow odors to travel.
- If you have a rarely used bathroom or laundry sink, pour a cup of water into the drain to top up that trap.
4. Clear the drain and disposal if needed
- If odors persist after refilling traps, run the garbage disposal with cold water for 20–30 seconds. Remove visible food scraps from the strainer.
- For routine freshening, flush with plenty of hot water and a little dish soap rather than strong chemicals.
What Not to Do
- Don’t leave traps dry after winterization—dry traps let odors enter.
- Don’t assume a brief pour of water is always enough; check unused fixtures and refill traps as needed.
- If refilling traps doesn’t help and smells spread, professional help may be needed.
When to Call a Professional
- The smell won’t go away after you refill traps and flush lines for several minutes.
- The odor is strong, chemical-like, or makes household members feel unwell—this could indicate leftover antifreeze or another contamination that needs safe handling.
- You notice multiple drains or plumbing fixtures smelling at once, or you suspect a venting or sewer line problem.
Safety Notes
- If antifreeze was used, know what type it was (propylene glycol is less toxic than methanol-based varieties). Ventilate the area while flushing and avoid inhaling fumes.
- Avoid pouring harsh chemicals down drains to mask smells; they can damage pipes, harm septic systems, or create dangerous fumes if mixed with other substances.
- If anyone in the home feels dizzy, nauseous, or ill from smells, leave the area and seek medical advice or professional plumbing help promptly.
Common Homeowner Questions
- Why did the sink only start smelling after I winterized?
A: The trap or lines were likely drained or contaminated and need to be refilled and flushed. - How long should I run water to clear antifreeze smells?
A: Run a steady stream for several minutes and repeat if needed until the smell is gone; ventilate while you do it. - Can I use bleach or store-bought odor removers to fix this?
A: Avoid harsh chemicals; simple water flushing and mild soap are safer. Call a pro if the smell persists or is strong.