My dilemma: Liquid or bar soap?

Question

“I like the convenience of liquid soaps, but wonder about what’s in them – plus they seem to have more packaging than bar soaps. So which one is better for the environment?”

Helen H, Green Ideas reader

Answer

“Soapy suds are big business in New Zealand, and last year we spent $74 million scrubbing the dirt from our skin. So yes, the type of skin-cleaning product you pick can have a big impact on your environmental footprint.

Recently there has been a trend to pick liquid soap over bars due to rumours that old fashioned soap bars were unhygienic. People thought that shared contact with soap bars could transfer bacteria, and that liquid soap from single-dispense bottles got around this problem. However science has disproved this by showing that when bacteria such as E. coli are placed on a bar of soap the bacteria were not subsequently detected on the hands of a person who washed using it.

So if there are no real differences in cleaning ability, what are the important environmental factors to consider?

Looking at ingredients first: bar soap is made by adding lye (sodium hydroxide) to animal or vegetable fats or oils. Almost all soaps use palm or coconut oil so check that you are buying from environmentally aware manufacturers who use sustainably sourced palm oil.

Most liquid soaps on the other hand are actually synthetic detergents. Several of the ingredients used in them are derived from petroleum products.

As for packaging, bar soaps tend to use less. Try to avoid those with unnecessary plastic overwraps and choose those in biodegradable cardboard boxes.

Liquid soaps come in plastic bottles so they are always going to be more energy-intensive to produce – though you can reduce the overall life-cycle energy cost by picking a container that is recyclable.

Lastly, with the main ingredient of liquid soaps being water, they are heavier and bulkier than bar soap and require more fossil fuel energy to transport an equivalent amount.”

Dr Michelle Dickinson

The verdict

With a carbon footprint 25 per cent smaller than liquid soaps, bar soaps are the clear winner for a greener clean.

Have an eco dilemma that needs expert advice? Email [email protected] with 'My dilemma' in the subject line, or write to Green Ideas, PO Box 47177, Ponsonby, Auckland 1144.