Bar soap or liquid soap: which is better for the environment and your wallet?

Can we talk about handwashing? It used to be all we talked about. Washing your hands was of national importance just a few years ago. There were even videos on how to do it properly. Scrub all surfaces of the hands – including the back of hands, between fingers and under nails – for at least 20 seconds. That’s long enough to sing the full Happy Birthday song, twice.
With the HSE warning of serious respiratory infections this winter, handwashing is back on the agenda.
Both liquid and bar soap are equally effective at washing hands. Although germs may stay on a bar of soap between washing, studies have consistently shown that this does not impact the efficiency of the soap. There is no evidence to suggest that “antibacterial” ingredients in soap improve their cleaning power either.
But which is greener: bar soap or liquid soap? It depends on the ingredients, the packaging and how much water you use, experts say.
Bar soap, made from plant oil or animal fat and lye, without many extra ingredients is more environmentally friendly than liquid soap. Indeed, bar soap cuts greenhouse emissions by about a third compared with liquid soap, according to a study from the Institute of Environmental Engineering at the Swiss university ETH Zurich.
Surfactants in soap enable it to mix into water, helping the cleaning agents remove dirt. Soaps made with surfactants from petroleum, are actually “detergents”. Making detergents uses five times as much energy and produces about 10 times as many greenhouse emissions as making simple soap, according to the Swiss researchers.
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Some households use liquid soap dispensers. A branded supermarket version retails for about €3.50 for 300ml. When it’s empty, you buy another.
If soap dispensers are part of your regular shop, you can save yourself money and reduce the environmental impact by refilling the ones you have, and refilling them with something environmentally friendly.
Instead of continually buying individual soap dispensers, where the pump part is hard to recycle, or buying refill pouches that you may or may not be able to recycle, you could go big. A 5-litre container of Ecover lavender and aloe vera hand soap refill, for example, costs about €46 excluding delivery from Earthmother.ie. That’s a potential saving of about €10 on buying the equivalent amount of soap in individual branded soap dispensers from the supermarket.
Alternatively, a 5-litre bottle of Bio D cleansing fragrance-free hand wash is €29, excluding delivery, from Mayo-based Pax Wholefoods. That’s €27 less than buying the same amount of soap in branded individual dispensers from the supermarket.
Refill your old 300ml soap dispenser with this and it will cost you just €1.74. That’s a saving of €1.69 per dispenser. The container is made from 100 per cent recycled plastic.
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Refill pouches are usually made of a soft plastic – that’s plastic you can scrunch in your hand. You can now put this in your recycling bin due to advancements at recycling facilities in Ireland and access to new markets where this material can be processed, according to MyWaste.ie.
But you have to make sure the pouch is clean and dry, which means no liquid left in it. If you can’t, put it in your general waste bin, says MyWaste.ie.
When it comes to being green, bar soap wins on packaging – packaging liquid soap is 19 times as energy-intensive as packaging bar soap, according to the Swiss study. Also, liquid soap is mostly water and distributing it creates nearly eight times as many carbon emissions as an equivalent amount of bar soap, according to the Swiss study.
Some soaps, bars or liquid soaps are based on petrochemical surfactants that come from oil – these don’t degrade well and can be toxic to aquatic life. When buying soap, look for one that uses plant-based surfactants, which are renewable and biodegrade easily.