Silica gel is most commonly encountered in everyday life as beads packed in a semi-permeable plastic. In this form, it is used as a desiccant to control local humidity in order to avoid spoilage of some goods. Because of poisonous dopants (see below) and their very high absorption of moisture, silica gel packets usually bear warnings for the user not to eat the contents, but to throw them away instead. If consumed, the pure silica gel is unlikely to cause acute or chronic illness, but would be problematic nonetheless.

Silica gel's high surface area (around 800 m²/g) allows it to adsorb water readily, making it useful as a desiccant (drying agent). Once saturated with water, the gel can be regenerated by heating to 150 °C (300 °F) for 1.5 hours per litre of gel. Some types of silica gel will "pop" when exposed to enough water.