Practical guide

Why a Sink Can Smell Like Rotten Eggs

First locate the odor: drain, overflow, hot water, cold water, or cabinet. That location changes the next check.

Quick answer

Compare hot water, cold water, the drain, and the cabinet separately, then note whether other fixtures share the odor.

Drain buildup, a dry trap, water-heater conditions, and nearby sources can sound similar. Test one location at a time.

Fill a clean glass and move away from the sink before smelling it, then compare with the drain and overflow.

If the odor fills the room, appears near fuel-burning equipment, or comes with leakage, contact the relevant utility or qualified professional.

Question	First option	Second option	Takeaway
Where is it strongest?	Drain or overflow	Water sample or whole room	Keep the next check tied to the location.

Drain opening: Note whether the odor is strongest before or after water runs.
Overflow: Check whether the smell is concentrated at the overflow.
Hot versus cold: Compare separate samples away from the fixture.
Cabinet and room: Look for moisture and note whether the odor exists beyond the sink.

Indoor air quality guide
U.S. Environmental Protection Agency. Ventilation and household odor source context. Use this for general context and confirm product instructions, local conditions, and qualified help when work exceeds routine maintenance.
Improving indoor air quality
U.S. Environmental Protection Agency. Ventilation and household odor source context. Use this for general context and confirm product instructions, local conditions, and qualified help when work exceeds routine maintenance.

Bathroom guides
Use the bathroom hub to compare ordinary drain, overflow, and surface cleaning routines before escalating.
Maintenance priorities
Move any observed leak or ventilation concern into the seasonal work list with an owner and date.