Why Does My Sink Smell Like Rotten Eggs?

Use the glass test to separate water odor from drain/overflow odor, then compare hot and cold.

Updated September 15, 2026Safety-aware troubleshootingNo professional inspection implied

Quick answerWhen a sink seems to smell like rotten eggs, determine whether the smell is in the water or at the drain. Fill a clean glass and carry it away from the sink. If the glass is fine, focus on the drain/overflow; if the water itself smells, compare hot and cold across several fixtures.

Safety / escalation noteIf the sulfur-like smell is actually in room air and gas equipment is nearby, leave and follow gas-leak guidance rather than assuming the sink is responsible.

60-second diagnosis

Does a glass smell away from the sink?
Is hot water worse than cold?
Is odor strongest at the overflow opening?
Does only one sink have the problem?
Is there gas equipment nearby?

Likely causes, ranked by fit

Drain/overflow residue

Common

Best fit: Glass test is clean; odor stays at sink opening.

How to check: Inspect stopper/overflow.

What fixes the source: Physically clean accessible residue.

Hot-water odor

Possible

Best fit: Hot water smells at multiple fixtures.

How to check: Compare hot/cold.

What fixes the source: Water-heater evaluation.

Source-water sulfur odor

Possible

Best fit: Cold water in glass smells at multiple fixtures.

How to check: Identify public versus well supply; consider testing.

What fixes the source: Water-system treatment based on measured conditions.

What to do now

Perform the glass-away-from-sink test.
Compare hot and cold.
Clean stopper/overflow if water itself is odor-free.
Escalate source-water issues to utility/lab or water professional.

Do not do this

Do not mix cleaners in the drain or assume sulfur odor proves water contamination without testing.

When to call a professional

Gas emergency service for plausible gas leak; plumber/water professional for persistent water or drain issues.

Questions people ask

Why does the smell vanish when I leave the sink?

The drain or overflow may be emitting odor while running water stirs the air, even if the water is fine.

What if only hot smells?

That points toward the water heater.

What if only one faucet smells?

A local fixture/drain/plumbing branch is more likely than a whole-water-supply problem.

Primary safety/reference sources used on this guide

U.S. PHMSA — Recognizing and responding to natural-gas emergencies — Natural gas is odorized and may smell like rotten eggs; PHMSA advises leaving the area and avoiding switches, phones, flames and engines near a suspected leak.

This information is educational and cannot verify a leak, electrical fault, mold condition, water quality result, plumbing-code issue or appliance failure remotely. When there is immediate danger, follow local emergency guidance.