Stop Washing at 40°C: What Laundry Temperatures Actually Work

Think laundry is simple? Your wash temperature might be wrong — and your clothes could be harboring bacteria.

What washing temperature should you prefer?

Chris van Tulleken — an Oxford graduate, molecular virologist, associate professor at University College London, infectious disease doctor, and TV presenter — told BBC Morning Live that people often wear clothes teeming with microscopic pests.

He explained that wash temperature plays a key role in killing microbes. But hotter water isn’t always better.

While modern washing machines can reach as high as 90 °C, that’s unnecessary for most fabrics and it can significantly increase electricity bills. “This temperature kills not only bacteria but also your clothes,” Dr. van Tulleken warned. He added that if clothes are so dirty they need that kind of heat, it’s better to “buy new clothes.”

However, if you or a family member is ill, Dr. van Tulleken advises washing laundry at 60 °C. This temperature will eliminate pathogens like norovirus, following official World Health Organization recommendations.

For everyday laundry, there’s no need to set the machine to 40 °C. He says that’s “too cold to kill anything”; it also takes longer and costs more.

“30 degrees is perfectly sufficient, and it’s much cheaper. Switching from 40 to 30 °C saves nearly 40 percent on energy costs,” Dr. van Tulleken noted.

What temperature does he consider optimal?

He told viewers he personally prefers an even lower temperature — a relatively cool 20 °C, which he says “saves 62 percent of your money compared to 40 °C.” The only exception he makes is for sportswear, which he washes at a slightly warmer setting, the Daily Mail reported.

Dr. van Tulleken says that in other cases he uses a detergent formulated for cold water when washing at 20 °C.

He’s also strict about washing machine hygiene — something he says many people neglect.

Your washing machine needs to be clean!

A common problem is mold building up in the detergent drawer, he said. He washes the drawer in the dishwasher and wipes the drum with a cloth slightly dampened with vinegar.

To keep the machine running well, he suggests: empty the filter every three to six months; clean the detergent tray monthly; clean the rubber door seal weekly; and leave the door open when the machine is not in use.

A dirty washing machine typically causes a moldy smell in clothes, especially if damp items are left in the drum for long periods.