Garages experience big temperature swings. Cleaning expert Noah Pinsonnault explains that heat can speed up the breakdown of ingredients and raise pressure inside aerosol cans, while cold can also alter formulas.

Bleach is especially vulnerable. Andrew Brown, owner of U.S.-based Immediate Movers and Storage, notes that high temperatures speed up the loss of active chlorine, and he has found garage bottles with peeled labels and swollen seams.

Basements are often damp. Pinsonnault adds that humidity can damage packaging and reduce the power of products that need to stay dry. Oxygen‑based powdered cleaners, for example, deteriorate faster when exposed to moisture and heat.

Under‑sink cabinets hide another risk. They can conceal water leaks and give children or pets easy access. Brown said he removed about 40 cabinets where leaks went unnoticed until the homeowners moved out.

The U.S. National Capital Poison Center advises that cleaners should never be stored alongside groceries, and they must never be transferred into glasses, cups or water bottles.

FamilyDoctor.org warns that placing cleaners on open shelves or in decorative jars puts them within children’s reach and can hide important safety labels, increasing the chance of accidental ingestion.

A cool, dry indoor cabinet or hall closet, kept out of reach of children and pets, is the safest option. Keep products in their original, clearly‑labeled containers and use child‑proof locks when needed.