Modern washing machines allow you to choose different temperatures, but 40°C is not always the best option.
Bacteria: Washing at 40°C does not completely eliminate bacteria and dust mites. Higher temperatures, such as a 90°C cycle, are more effective against them, if the fabric allows it.
Stain removal: Temperature is not the only factor in effective stain removal. The amount and quality of detergent, the performance of the drum and the oxygen systems of modern machines play a big role.
Important: Always follow the instructions on the garment label. Many fabrics require a 30°C or delicate wash, as high temperatures can fade colors and damage the fabric.