Dishwashers

Zeolite is a magic mineral that dries dishes—here's how

More dishwashers are using zeolite to mitigate moisture, but how does it work?

Zeolite granules in jars. Credit: Reviewed

By clicking one of our links you're supporting our labs and our independence, as we may earn a small share of revenue. Recommendations are separate from any business incentives.

There are rocks that can get your dishes dry. No, seriously: The mineral is called zeolite, it turns water into heat, and it’s coming to a dishwasher near you.

Zeolite was first used in high-end Thermador dishwashers in 2008, but this year the technology was integrated into sister brand Bosch’s 800 and Benchmark series dishwashers. Since the technology is becoming more mainstream, it’s a good time to review exactly why this mineral is being used in more dishwashers and why it might be the key to better drying.

People hate wet dishes. Drying dishes is energy expensive. Zeolite dries at a fraction of that energy.

Dishwashers, historically, have had two tricks for ensuring dry dishes: a heating rod and very hot water. While these techniques might work on glassware and ceramics, plasticware doesn’t retain heat well and is notoriously hard to dry using these methods. There’s also the side-effect of making your dishes too hot to put away immediately. Zeolite solves all of these problems.

What is zeolite?

zeolite

Zeolite pebbles just look like small, greenish-beige stones, but their chemical properties should help make dishwashers much more energy efficient.

Zeolite’s properties sound unreal at first. As the mineral extracts water from its surroundings, it releases a significant amount of heat. With enough moisture, you can generate the energy required to boil water (so, yes, they’re too hot to touch). The water extraction happens through a process called adsorption (as opposed to absorption), a chemical reaction which bonds the water atoms to the surface of the zeolite and releases heat. The zeolite’s adsorption power can be regenerated by re-applying the released heat, which frees the stored water as vapor. This process doesn’t degrade the zeolite at all, meaning you’ll never need to replace the zeolite in your dishwasher.

It’s best to think of zeolite as a battery that can store heat or water. When it’s storing heat, it can release that heat to adsorb water. If it’s storing water, it can release the vapor and begin storing heat again. Bosch has leveraged these properties to extract moisture during the drying process, releasing heat, which is then blown back over the dishes to further aid drying. At the beginning of the next wash cycle, the dishwasher heats the zeolite granules, discharging the stored water and preparing the zeolite to adsorb more water in the next dry cycle.

zeolite compartment
Credit: Reviewed

The interior of Bosch’s dishwasher with zeolite tech. Zeolite is stored in the glowing-red cavity in the back, to remind you you’re harnessing the power of a volcano.

There’s a few benefits to using zeolite in this way. You know how opening the dishwasher after a cycle would engulf you in a cloud of steam? That’s been absorbed by the zeolite. Since dishes are getting dried by hot air, they should be warm to the touch, not piping hot. Because it takes less energy to heat a 1.2 kg container of zeolite granules than it does to heat an entire load of dishes, dishwashers that leverage zeolite in this way are able to use significantly less energy than other dishwashers.

People hate wet dishes. Drying dishes is energy expensive. Zeolite dries at a fraction of that energy.

What’s the downside?

When something sounds too good to be true, it typically is, especially when we’re talking about benefits that sounds downright magical. Zeolite’s main downsides are its price and availability. Previously, only three dishwasher models featured the zeolite technology, none of which were available in the U.S., and all of which cost at least $1,500. Now this technology is included in Bosch’s popular 800 series dishwasher, which have configurations available for around $1000. While this is still a significant investment, it does indicate the technology is becoming more accessible over time.

Is this the future?

You can’t argue with the science. Zeolite is quick, efficient, self-replenishing, durable, and—quite frankly—awesome. Based on what we know now, integrating zeolite into a dishwasher really seems like one of those innovations that gradually might revolutionize the dishwasher industry. But for now, Bosch owns the technology. We’re looking forward to more of its dishwashers leveraging this mineral to give us drier dishes. Who wouldn’t want to say they dry their dishes with powerful lava rocks?