Musty smell under the kitchen sink? Check moisture first

The short answer

A musty smell is a reason to look for moisture before trying to deodorize the cabinet. It does not prove mold or tell you where water is coming from.

Empty the cabinet, document what you see, dry movable items, and check whether moisture or odor returns after ordinary sink or dishwasher use. If water returns or the cabinet is damaged, the next step is maintenance or a qualified professional—not fragrance, more storage, or a new liner.

First, make sure the smell is actually musty

This guide is for a damp, earthy, or musty cabinet odor. A sewer-like, rotten, burning, or strong chemical smell is a different problem. Do not try to identify or repair an unfamiliar odor by following a generic cleaning hack. Stop using the area when appropriate, ventilate safely, and use the relevant landlord, maintenance, plumbing, utility, or emergency process.

Empty the cabinet without disturbing the plumbing

Remove stored items so you can see the cabinet floor, back, sides, and the area around visible pipes. Do not disconnect, tighten, or move plumbing. Keep hands, paper, and cleaning tools away from disposal wiring, outlets, and other electrical components.

Record the starting condition before wiping anything:

• damp spots, droplets, or condensation;
• dark stains or rings;
• swollen, soft, peeling, or warped cabinet material;
• rust or residue near a connection;
• a wet sponge, cloth, trash liner, or leaking product container; and
• whether the smell is strongest at the cabinet floor, stored items, drain, or trash area.

The US EPA's kitchen-cabinet guidance notes that leaking pipes under a sink can lead to mold in walls or cabinets and should be fixed by a qualified professional. The CDC says mold can smell musty and grows where moisture is present. Neither source says an odor alone identifies mold or the cause.

Try one no-buy return-moisture check

If there is no active water, visible mold, damaged material, or unfamiliar equipment, dry the clear cabinet floor and movable items. Place a loose sheet of plain paper on an open floor area where it will not touch pipes, wiring, a disposal, or stored chemicals. Do not wrap or tape paper around a connection.

Use the sink and dishwasher normally, then recheck the same day. Record any new wet mark, condensation, stain, or return of the odor. A wet result is useful evidence for a maintenance request. A dry result does not rule out a hidden or intermittent leak, condensation, drain problem, or mold behind a surface.

Do not mask the source

Fragrance, baking soda, vinegar, lemon, a moisture absorber, or a cabinet liner may change the smell without correcting the moisture source. Do not combine cleaning products. Follow every product label and confirm that any cleaner is compatible with the cabinet surface.

EPA guidance says the key to mold control is moisture control: fix the water problem and dry wet materials. It also warns that hidden mold investigation can require an experienced professional. A quick deodorizing result is not evidence that the cabinet is dry or the underlying problem is solved.

Know the stop signs

Use the appropriate landlord, maintenance, plumbing, or remediation path when you find:

• active dripping, pooling, or moisture that returns;
• softened, swollen, warped, or delaminating cabinet material;
• visible mold or a persistent musty odor with no visible source;
• water near electrical or disposal components;
• sewage or contaminated water; or
• health symptoms or a cleanup area you are not equipped to assess.

Renters should document the date, odor, visible condition, and any returning moisture without storing private photos on this site.

Organize only after the cabinet stays dry

Once the source is addressed and the area is dry, use the under-sink measurement guide to map pipes and access. Then follow the access-first organization guide so future storage remains removable and does not hide the cabinet floor.

Bottom line

Find and document the moisture before fighting the smell. If water or odor returns, escalate the cause instead of covering it with a deodorizer or storage product.