Why soap & water is your best defence against Covid-19

There is an absolute plethora of information coming thick and fast about Covid-19 and how to prevent the spread of the virus.


Distressingly, people are also releasing and then sharing information that is not correct and that could cause harm (aka DIY hand sanitisers) - which is the last thing anyone needs!


I want to explain why soap (or surfactants) and water are the best defence you have against the virus (alongside social distancing) as well as combat a couple of myths about hygiene, specifically hand sanitisers, that you may have come across.


We talk a lot about how our shampoo bars are soap-free and how pH matters for your hair (not so much for your skin). If you want to read this for some context on the below, please find another article here.

What is a virus?

The virus that causes Covid-19 (the disease) is called SARS-CoV-2 and is spread in respiratory droplets and through touch – like a handshake or hug. As droplets are heavy, they drop to the ground quite quickly – within 2m or so. However, this virus can also survive on surfaces for quite some time (up to three days on plastic), depending on the surface. So a big part of the way you can be infected is through your hands and touching your face.

To be pedantic, you can’t kill a virus, because they are not actually classified as alive. You can render them inert, but as they are non-living, they cannot be killed.

A virus is essentially a loop of genetic material, encased in a protective protein coat. They do not possess their own organelles (cellular machinery), so rely on a host cell to replicate. They cause us harm by invading our cells and hijacking the organelles to create hundreds of copies of the original.

Some viruses also have another coating – a phospholipid bilayer that protects them – a little like a bubble. These are classed as enveloped. Happily for us, the family of coronaviruses – which of course SARS-CoV-2 is a part of - all have this lipid bilayer. This protective coating makes them susceptible to desiccation and heat – as well as chemicals, in particular, detergents. Norovirus, for example, has no lipid bilayer and can last on surfaces for months.

There are many, many types of viruses classified by their genetic material type and structure. So for the sake of simplicity, from here on out, I am only talking about the family of coronaviruses (which if you are wondering, are positive-sense single strand, RNA viruses).

Have I lost you yet? Bear with me!

How does something clean?

There are essentially two types of bars out there:


Soap bars – these are made up of fats and oils mixed with a strong alkali, such as sodium hydroxide, which makes for a great bubbly bar with a high pH. Our bodywash bars are made of soap - though we don’t recommend these for hair, they are great for the skin.


Syndet bars - short for synthetic detergent.

These are what real shampoo bars are based on. These bars are made up of surfactants (short for SURFace ACTive AgeNTS) have a much lower pH (anywhere from 3-7 depending on formulation) and are much gentler on hair because of it. They can also be used on the skin. Again, for a more thorough explanation of the differences, please read here.


The question we’re getting a lot right now is “If our bars are soap-free, will they then also destroy the virus?”

The answer is yes! Even though soap bars and surfactant-based bars are chemically different in some ways, when it comes to cleaning, they operate in a very similar way.

This is a soap molecule





and this is a surfactant molecule.


They look very similar, right? That is because soap IS a surfactant, but it is just created in a different way resulting in the different chemical properties they exhibit.


Surfactants are amphipathic – this means they have one end which is lipophilic (loves oil and fats – also referred to as hydrophobic) and one end which is hydrophilic (loves water).


In a solution of water, the lipophilic end will be attracted to and bond to a fat or oil particle, whilst the hydrophilic end sticks into the water.


A group of surfactant molecules cluster together to create a micelle, which essentially surrounds the oil or fat in a sphere with all the water-loving tails sticking out so the oil which of course wouldn’t normally mix with the water, is emulsified into the solution.



So how does a surfactant (or soap) destroy viruses?

Well, … it goes back to the lipid bilayer.

Lipids are fats, so upon application of soap and water to your hands, the lipophilic end of the surfactant molecule attaches to the protective coating bilayer of the virus, whilst the hydrophilic end remains anchored into the water.

You rub your hands together for twenty seconds, create lots of bubbles, lots of friction then rinse it all off down the drain – complete with all the viral particles that have been bonded to the surfactant molecules – which are of course rinsed off with more water.

What’s more, because the bonds holding together a virus are quite weak, this same interaction breaks apart virus particles which very quickly destroys the virus.

So washing your hands with almost anything that foams or creates bubbles will work. And despite what you might read, an antibacterial solution isn’t necessary because bacteria and viruses are very different and for this virus, soap works just fine.

What about hand sanitisers?

Alcohol-based sanitisers are a good second option, but you do need to use a good dollop and slather it on your hands for 15-20 seconds to ensure it works. As you need more alcohol gel to do the same job as soap and water, the likelihood you will miss spots is slightly higher.


The alcohol percentage needs to be at least 60%, though 70% is better. So a lot of the ‘recipes’ online are woefully inadequate. Don’t even get me started on the ones that just rely on essential oils – they will not work! Alcohol based sanitiser don't work on all microbes, but luckily they do on enveloped viruses.

But soap and water is definitely your best option.

What will work:

  • Bars of soap - just like our bodywash bars.

  • Dishwashing liquid

  • Most general purpose sprays

  • Syndet/soap combo bars like Dove

  • Syndet bars like our solid shampoos

  • Liquid soaps

  • Hand sanitiser with over 60% alcohol content

What will not work:

  • Vodka, rum or any other spirits you have in the cupboard. Very few of these have a high enough ethanol content – most around under 40%. You’re better off drinking it and staying at home.

  • DIY hand sanitisers that are alcohol-free and contains only essential oils and aloe vera gel. The people who are peddling these are either misinformed or lying to you and should be ashamed of themselves.

  • Undiluted essential oils. There are no scientific studies that prove essential oils have any effect on the virus that causes Covid-19 and using neat essential oils on your skin can cause sensitization and irritation issues.

Brianne West

New Zealand entrepreneur and founder of Ethique – the world’s first full range, zero-waste beauty brand. Cited as a ‘Global Thinker’ by Foreign Policy magazine in 2016 for “making beauty eco-friendly”. Named 2019 NZ EY 'Young Entrepreneur of the Year'.

  • LinkedIn
  • Instagram
  • Twitter