We are being encouraged to wash our clothes at ever lower temperatures – first it was 40 celsius then 30. It saves energy and money, but are there any disadvantages?

Reduce electricity bills and help the environment by washing at 30

Much of the electricity used by a washing machine while washing our clothes is used to heat the water. Therefore a good tip to save energy and cut electricity bills is to wash your clothes at lower temperatures. The often-quoted figure is that washing at 30 saves 40% more energy than washing at 40.

Marks & Spencer and Asda have tried to boost their green credentials by adding the message ‘wash at 30’ to their clothes labels which, in theory, should remind people to do just that. Ariel are also pushing the ‘wash at 30’ message, claiming that their newest detergent has ‘Cool Clean’ technology to improve the cleaning power at lower temperatures.

Washing at 30 may not remove stains

The biggest problem with washing at lower temperatures seems to be stain removal. Washing with any washing powder, or even no detergent at all, seems to produce acceptable results for everyday cleaning at 30C. However, removing grass stains, motor oil etc requires either higher temperatures or a biological washing powder.

Traditionally, if you use the same washing powder at 60C, 40C and 30C, you will get better cleaning results at higher temperatures. However, the enzymes added to biological powders often produce ‘high temperature’ results at lower temperatures. The effectiveness can be variable though, with some stains responding better than others.

Biological washing powders help stain removal at 30

Enzymes are proteins which help to break down substances which cause staining on our clothes. Some people claim to be sensitive to biological washing powders and prefer to use non-biological or ‘sensitive’ alternatives, although these are typically less powerful. There is no evidence that biological washing powders are any worse for the environment than their non-biological equivalents.

Depending on the results you get at lower temperatures, it may be better to wash all heavily stained clothes at 60, rather than washing them several times at 30 or 40. Many people recommend you also use high temperature washes when someone in the house is ill.

Ariel’s ‘Cool Clean’ detergent claims to have ingredients optimised to clean at 30C. However, the general opinion is that washing at 30 can be very effective using any detergent, and there is no need to use Cool Clean. Procter and Gamble, the manufacturers of Cool Clean, state that higher temperatures may still be required for stain removal.

Procter and Gamble have studied the environmental impact of using Cool Clean, compared to an older style Ariel detergent. It scores better in all categories except water consumption (which is the same), and aquatic eco-toxicity (which is slightly worse, although apparently the difference is not statistically significant).

High temperature washes are important to kill mould and allergens

Most washing machine manufacturers recommend you carry out a high temperature wash, with a washing powder that contains bleach, at least once a month, to keep the washing machine free of bacteria and mould that can build up if you only wash at low temperatures.

Allergy sufferers could have a problem with low temperature washes. Korean researchers have shown that washing at 30 or 40 is much worse at removing dust mites and pollen than washing at 60. However, they do say that several cold water rinses at the end of the cycle improves results considerably, so a washing machine which rinses really well could help allergy sufferers.

Other tips for killing dust mites include adding tea tree oil to your wash, and drying clothes in sunlight.

Environmentally friendly washing tips

Other environmentally friendly washing tips include ensuring you always wash full load, using the ‘economy’ setting on your machine, using eco-friendly washing powder brands like Ecover and not using a tumble dryer. Also, you may not need as much detergent as you think for normal loads – especially if you live in a soft water area.