Mothballs don’t dissolve easily in water. They’re made of solid chemicals, either naphthalene or paradichlorobenzene, that are nearly insoluble in water (naphthalene dissolves at just 30 mg per liter at room temperature). Instead of truly dissolving, mothballs slowly turn from solid directly into gas at room temperature, a process called sublimation. So the approach you need depends on why you want them gone: speeding up their disappearance, removing them from a surface or pipe, or getting rid of the smell they leave behind.
Why Mothballs Resist Water
Both naphthalene and paradichlorobenzene are organic compounds that repel water. Pouring water over a mothball, or even soaking one, will barely shrink it. You’d need roughly 3,300 liters of water to fully dissolve a single 100-gram mothball at room temperature. Hot water speeds things up slightly but not enough to be practical. Boiling water poured over mothballs in a drain, for instance, won’t dissolve them and risks pushing them further into your plumbing.
Solvents That Actually Work
Naphthalene dissolves far more readily in alcohol and similar organic solvents. It dissolves at about 7.7 grams per 100 mL in ethanol or methanol, roughly 250 times more soluble than in water. Acetone works even faster on both naphthalene and paradichlorobenzene mothballs.
However, there are real safety concerns with this approach. Naphthalene has a flash point of 79°C (174°F), and mixing it with flammable solvents like alcohol or acetone creates a fire hazard. Work in a well-ventilated area, away from any heat source or open flame. If you’re dissolving mothballs in a container, do it outdoors. Never pour solvent-mothball mixtures down a drain, both because of fire risk and because acetone will damage PVC pipes.
Letting Them Evaporate Naturally
The simplest way to get rid of mothballs is to let sublimation do the work. At room temperature, mothballs release their chemicals as gas at a steady rate. Research from the National Research Council of Canada measured naphthalene mothball emissions at 841 to 1,015 micrograms per gram per hour, which means a standard mothball will shrink noticeably over weeks and disappear completely over several months.
You can speed this up significantly by increasing airflow and temperature. Place mothballs in direct sunlight or a warm, breezy spot and they’ll evaporate much faster. Spreading them out so more surface area is exposed to air also helps. In a sealed closet with no ventilation, the same mothball could linger for a year or more.
Removing Mothballs From Drains or Tight Spaces
If a mothball has fallen into a drain or pipe, dissolving it in place is tricky. Acetone would work chemically but damages PVC plumbing. Your best options are mechanical.
- Shop vacuum: Attach a narrow, flexible hose and try to suction the mothball out. Creating a tight seal over the drain opening improves suction.
- Drain air gun: These tools pump compressed air into the pipe to dislodge blockages. They’re available at hardware stores and can push a mothball through to a wider section of pipe.
- Flexible retrieval tool: A plumber’s snake with a corkscrew tip or a grabber tool can physically hook and pull out the mothball.
If the mothball is in an accessible spot (a drawer, a storage bin, under a porch), just pick it up with gloves and dispose of it. Mothballs are EPA-registered pesticides, and naphthalene has been linked to nasal cancer, so avoid handling them with bare hands or breathing the fumes in enclosed spaces.
Getting Rid of the Smell
Even after mothballs are gone, the odor lingers on clothing, wood, and fabric because the chemicals bind to porous surfaces. A few household methods work well for clearing it out.
For clothing, spray garments with a 50/50 mixture of white vinegar and water, then launder them with half a cup of vinegar in place of detergent. You may need to repeat this two or three times for heavily saturated items. Sun-drying clothes outdoors accelerates the process since heat and airflow help release trapped naphthalene.
For rooms, closets, and furniture, wipe hard surfaces with vinegar or a baking soda solution. Place bowls of white vinegar, activated charcoal, or coffee grounds around the space to absorb lingering fumes. Activated charcoal is especially effective because it traps organic compounds rather than just masking the scent. Leave bowls out for several days, replacing them as needed. Adding a few drops of essential oil to vinegar bowls can offset the vinegar smell while you wait.
For wood furniture or flooring, the smell can persist for months because naphthalene penetrates deep into the grain. Repeated vinegar wipe-downs combined with good ventilation are the most reliable approach. Sealing the wood with polyurethane or shellac after cleaning can also lock in any remaining odor.