Your Washing Machine Might Not Eliminate Harmful Bacteria from Your Clothes

Washing clothes in warm water at 60°C (140°F) might not effectively eliminate harmful bacteria.

Studies indicate that contaminated fabrics can remain infectious for weeks. Moreover, washing with detergent at 60°C can remove bacteria and tackle stubborn stains.

For example, NHS England advises healthcare workers to wash uniforms at 60°C for a minimum of 10 minutes to eliminate nearly all microorganisms, according to Katie Laird from De Montfort University in Leicester, UK. “However, it’s unclear what the machine is truly accomplishing.”

Laird and her team examined six models of home washing machines to evaluate how effectively they cleaned contaminated fabric samples, specifically testing for Enterococcal feces, known to cause various infections, including urinary tract infections.

Their findings revealed that half of the washing machines tested failed to adequately disinfect clothing, reducing bacteria levels by at least 90% in only the rapid cycles; one-third of machines did not achieve sufficient breakdown even in standard cycles.

“This is primarily because most machines either don’t maintain or reach the expected temperature, particularly in shorter cycles,” notes Laird. “In one instance, we found a machine operating at just 20°C (68°F), which the user was unaware of.”

After analyzing bacteria across multiple washes, Laird’s team discovered that microorganisms began developing resistance to detergents. DNA sampling indicated that these microorganisms were acquiring genes that enabled their survival.

The findings suggest that utilizing home washing machines to launder medical uniforms could inadvertently facilitate the spread of infections and antibiotic resistance within hospital settings, Laird pointed out.

To reduce bacteria and viruses in household washing machines, Laird recommends regularly using a machine sanitizer, conducting 90°C (194°F) cleaning cycles, and employing descaling solutions to prevent the build-up of scale that may impair the heating elements’ function.