Quick Answer:
A metallic smell after a plumbing repair is usually caused by either metal filings or solder flux left in the lines, new metal parts (like brass or stainless components), or hot-water issues linked to the water heater. Start by running the cold and hot taps separately to see whether the odor comes from the cold supply, the hot supply, or the drain. That isolation tells you the most likely source and the next steps.
Why This Happens
- Metal filings or shaving left behind during installation can sit in the pipes and give a metallic odor when water flows.
- Solder flux used when joining copper can leave a smell until the lines are flushed.
- New brass or stainless parts sometimes release odors until they’ve been flushed several times.
- If the smell appears only with hot water, the water heater or its sacrificial anode can be producing metallic or “rotten” smells.
- If the odor seems to come from the drain rather than the water itself, the repair could have disturbed the P-trap or created pockets where debris sits; consider whether the repair changed drain performance. See Drain performance changed after repair.
Step-by-Step What to Do
1. Isolate the source by running taps separately
- Turn on the cold tap only and let it run for about 1–2 minutes. Smell the water coming from the tap (cup the water if needed). Note whether the metallic smell is present.
- Turn off the cold, then run the hot tap only for 1–2 minutes and smell again. If the odor is only on hot, the problem is likely the water heater or hot-side plumbing.
2. Flush the lines
- Run cold water for 3–5 minutes to clear any loose filings or flux. Then run hot for 3–5 minutes if it’s safe to do so (monitor scalding risk).
- If you have a filtered or drinking faucet, flush those lines separately too.
3. Check fittings and aerator
- Remove the faucet aerator and inspect for metal shavings or debris. Rinse the aerator and screen and reinstall.
- Inspect visible supply lines and fittings for loose metal particles or pipe dope residue and wipe clean.
4. Test where the smell is strongest
- If the smell is only at one sink, try running a different sink in the house. If other sinks are fine, the issue is likely local to the repaired area.
- If the kitchen sink is slow or draining oddly after the repair, that can trap water and cause odd smells — check whether the sink is running freely. If you noticed reduced flow, the issue may be related to a slow drain. See Sink slow after faucet install.
5. Inspect the water heater if hot water is the issue
- If the smell is only with hot water, consider flushing the water heater and checking the anode rod (this is a common cause of metallic or sulfur-like odors). If you’re not comfortable with the heater, call a technician.
6. Recheck after cleaning and flushing
- After flushing and cleaning aerators/fittings, run cold and hot separately again to confirm the smell is gone.
- Keep a note of any persistent smell and when it appears (hot only, cold only, or when water sits for a while).
What Not to Do
- Do not assume metallic smells will fade.
- Do not drink water you believe is contaminated; use bottled water until the source is identified if you have concerns.
- Do not pour strong chemicals or drain cleaners into the sink as a first step—these can react with metals or damage finishes and seals.
- Do not try to remove or alter water heater components (like the anode) unless you are confident and know how to do so safely.
When to Call a Professional
- If the metallic smell persists after flushing and checking aerators and fittings.
- If the smell is present only in hot water and you’re not comfortable inspecting or flushing the water heater.
- If you find metal filings embedded in fittings or evidence of damaged piping that you cannot safely clean or replace.
Safety Notes
- Be cautious with hot water—run hot water only long enough to test and avoid scalding.
- Turn off water at the shutoff valves before working on fittings, and protect surfaces from spills.
- Wear gloves and eye protection if you remove aerators or work near potentially sharp metal debris.
- If you detect a chemical smell in addition to metallic odor, ventilate the area and stop testing until you identify the source; some chemicals can be hazardous.
Common Homeowner Questions
- Q: How long should I flush the lines?
A: Start with 3–5 minutes for each supply (cold and hot) and repeat if you see debris; longer flushing is safe but monitor water use. - Q: Could a new faucet cause the smell?
A: Yes—new metal parts or residues from manufacturing and shipping can cause odors until flushed away. - Q: Is the water safe to drink after a repair?
A: If you smell metal, avoid drinking until you flush the lines and confirm the odor is gone; contact a pro if it persists.
For more related articles, see the Post-Repair Sink Drain Problems hub.