Why washer-dryer uses water even when drying

August 19, 2025 | 11:57 pm PT

Washer-dryers consume water when drying as many models use tap water to cool hot, humid air, allowing moisture from clothes to condense and drain away.

VnExpress reader Huynh Nguyen asked: "I only use the drying function on my newly purchased Panasonic washer-dryer, but I notice the machine still draws in and drains a large amount of water. Is this a defect?"

"Because my new home has limited space, I opted for a washer-dryer, even though my family previously used separate washing and drying machines. The old dryer only released a small amount of water during operation.

"With the new washer-dryer, however, I see it draining large amounts of water, almost like during a wash cycle. When I checked the inlet hose, I also found the machine was still taking in water while drying. I contacted the seller, who said this was normal, but it seems illogical to me.

"I would like experts and readers with experience to explain."

A washer-dryer and a standalone dryer from a home appliance brand. Photo by VnExpress/Tuan Hung

In response to the reader’s question, home appliance specialist Canh Manh Tien said: "It may come as a surprise, but many washer-dryers on the market, including models from Panasonic, LG, and Electrolux, do use water during drying."

This is a major difference from standalone dryers, which either vent moisture out or collect it in a container without requiring water, he said.

According to a manufacturer, condenser-type drying systems circulate hot air inside the drum to absorb moisture from clothes. The humid air is then cooled through a heat exchanger to condense into water, which drains away. In many washer-dryers, the cooling process uses cold tap water, so it is normal for the machine to continue drawing water while drying.

Tien added that washer-dryers can still operate without water if the supply is cut off. In such cases, the system relies on ambient air for cooling, but the process takes longer and consumes significantly more electricity.

"In some of my tests, the drying cycle alone in certain washer-dryer models consumed 60–80 liters of water per load, similar to what a front-loading washing cycle typically requires," he said.