Does Vinegar Kill Mold?

Does vinegar kill mold? Partly. Plain white vinegar is a mild acid that kills some common household molds on contact and does little to others, so it is a reasonable choice for small surface patches and a poor one for anything larger or deeper. It will not fix mold that has grown into drywall, insulation or carpet, and it does nothing about the moisture that caused the growth.

Does vinegar kill mold of every kind?

No. Household white vinegar is roughly 5% acetic acid. That is acidic enough to stop some molds and not acidic enough to stop others, and results vary with the species and how long the vinegar stays wet on the surface. You have no way of knowing which species is on your windowsill, so you cannot count on a kill. Treat vinegar as a cleaning aid that helps on some jobs, and do not treat it as a disinfectant with a guaranteed result.

It is worth remembering what cleaning mold is for. The aim is to remove the growth from the surface, and wiping and scrubbing do that whether or not the liquid in the bottle kills anything. Health Canada's own recommendation for small areas is water and dish detergent. Vinegar is an optional extra.

Where vinegar works reasonably well

• Light surface growth on window frames and sills where condensation collects in winter.
• Spotting on bathroom tile, grout and tub surrounds.
• Small patches on sealed or painted wood trim.
• Rubber door gaskets on front-loading washers and fridge seals.
• Hard plastic items such as bins, toys and the inside of a cooler.

The common thread is a small area, a surface the liquid can fully reach, and growth that has not gone deep.

Where vinegar does not work

• Drywall that is moldy through the paper. The growth is in the material, and wetting it with vinegar makes it damper.
• Insulation, carpet, underpad, ceiling tile and upholstery. These cannot be cleaned to a reliable standard and are normally removed.
• Attic sheathing or basement framing with widespread growth. The area is too large and the work throws spores into the air without containment.
• Anything still wet from an active leak or ongoing condensation. The mold returns as soon as the vinegar dries.
• Natural stone such as marble and limestone, which acid can etch, and some metals and finishes it can dull.

How to clean a small patch with vinegar

Health Canada counts one to three patches, each under a square metre, as small enough for a healthy adult to handle. For that size of job:

1. Wear rubber gloves, eye protection and a properly fitted N95 mask. Open a window.
2. Pour undiluted white vinegar into a spray bottle. Test a hidden spot first if the surface is finished.
3. Spray the patch lightly so it is wet but not running. On drywall, dampen a rag and wipe so the board does not get soaked.
4. Leave it for about an hour.
5. Scrub with a brush or rough cloth, then wipe with a rag dampened with water and a little dish detergent.
6. Dry the surface right away with a towel and a fan.
7. Bag the rags and put them in the outside garbage. Wash your gloves and your clothes.

The vinegar smell clears within a few hours. Check the spot weekly for a month. A clean surface that stays clean means the job is done. Regrowth means the surface is still getting wet.

Mixing vinegar with other cleaners

Do not mix vinegar with bleach. Acid and bleach together release chlorine gas, which is dangerous in a closed room. Do not combine vinegar and hydrogen peroxide in the same bottle either, since the mixture forms a more corrosive acid that irritates skin, eyes and lungs.

Vinegar and baking soda is a popular pairing. It fizzes, which looks like it is working, but the two largely neutralize each other and you are left with salty water. Baking soda on its own is a handy mild abrasive for scrubbing. Use one or the other. Tea tree oil and similar products get recommended online as well. We have not seen a good reason to pay more for them than for detergent.

When to stop cleaning and look for the cause

If you have cleaned the same patch twice and it has come back, a third round with a different product will not change the outcome. The surface is getting wet from somewhere. In houses around London the usual causes are winter condensation on cold window frames and outside corners, bathroom fans that are weak or vent into the attic, humid basements in summer, and slow plumbing leaks.

Start with the simple checks. Run the bath fan for 20 to 30 minutes after showers. Keep furniture a few centimetres off outside walls. Pick up a hygrometer and get basement humidity to about 50% or lower with a dehumidifier. Look under the nearest sink and at the ceiling below any bathroom. If the patch is bigger than you can cover with those steps, or the material feels soft, take photos and get it looked at before spending more on cleaners.

Common questions