Is Bar Soap Sanitary? What the Research Says

Key takeaways

• Used bar soap can carry bacteria on its surface, especially when it sits wet.
• Studies that deliberately contaminated soap bars found little or no transfer of those bacteria to hands after washing.
• Washing works because soap lifts oils, dirt and microbes from skin so rinsing can carry them away.
• A draining dish, a quick rinse of the bar, and personal bars when someone is sick are simple, sensible habits.

At some point, nearly everyone looks at a shared bar of soap and wonders: is bar soap sanitary? It is a fair question. A bar sits in a damp bathroom and gets handled by every member of the household. The good news is that this question has been studied, and the findings are reassuring. Here is what the research says, what it does not say, and how to keep your bar of chemical free soap clean with almost no effort.

Yes, Bacteria Can Live on Used Soap

Let us start with the honest part. Researchers who have swabbed used bars of soap, particularly in shared settings like clinics and public restrooms, have found bacteria on them. The wetter the bar and the more people using it, the more likely that is. Soap that sits in a puddle in a dish provides moisture, and moisture is what microbes need.

But finding bacteria on a bar is not the same as those bacteria ending up on your hands. That is the question that actually matters, and researchers have tested it directly.

What the Studies Found

A frequently cited study published in the journal Epidemiology and Infection in 1988 tested this by deliberately contaminating bars of soap with large numbers of bacteria, including E. coli, then having volunteers wash with them. Afterward, the researchers did not detect those bacteria on the volunteers' hands. An earlier study from the 1960s reached a similar conclusion. The authors concluded that washing with a contaminated bar is unlikely to transfer bacteria.

Those studies were small and done under controlled conditions, so they do not answer every possible question, and it is reasonable to read them with some care. They tested healthy volunteers with ordinary bars, not hospital settings or people with weakened immune systems. Still, the result fits with how soap works, and public health guidance on handwashing focuses on technique and time rather than on bar versus liquid.

Why Washing Still Works

Soap molecules have one end that is attracted to water and one that is attracted to oils. When you lather, soap surrounds the oils and grime on your skin, along with the microbes stuck in them, and lifts them away. Rinsing then carries everything down the drain. The surface of the bar gets rinsed in the same way as you use it.

The friction of rubbing your hands together and the rinse are a big part of the job. That is why the Centers for Disease Control and Prevention emphasizes scrubbing all surfaces of your hands for at least 20 seconds, then rinsing well under clean running water. Our guide to handwashing with natural soap covers technique in detail.

Bar vs Liquid: A Fair Comparison

	Bar soap	Liquid soap in a pump
Germs on the product surface	Possible on a wet, shared bar	Pump tops are touched by every user too
Contamination concerns	Mostly surface, rinsed off in use	Refilled dispensers that are topped up rather than cleaned have been linked to contamination in some studies
Best setting	Homes, personal use	Public restrooms, clinical settings
Packaging	Minimal	Plastic bottle and pump
Ingredients	Can be simple true soap	Usually synthetic detergent formulas

In hospitals and other healthcare settings, sealed liquid dispensers are generally preferred, and that makes sense where many people with weakened immune systems share a sink. At home, either works well. If you are curious why most liquid soaps rely on detergents, see why body wash needs sulfates and real soap does not.

Do You Need Antibacterial Soap?

For everyday use, the FDA has said there is not enough evidence that over the counter antibacterial soaps work better than plain soap and water at preventing illness. In 2016 it moved to stop the marketing of consumer antiseptic washes containing triclosan and many other active ingredients. Plain soap, used well, does the job. Read more in antibacterial soap vs plain soap, and for a deeper look at triclosan itself, the main site's guide to triclosan and antibacterial soap.

Simple Habits for a Cleaner Bar

1. Use a draining dish. A bar that dries between uses is less hospitable to microbes, and lasts longer too. See how to make a bar of soap last longer.
2. Rinse the bar. A quick rinse before and after use washes away surface residue and loose suds.
3. Clean the dish. Soap scum and standing water build up in dishes. Rinse or wash the dish every week or so.
4. Give each person a bar in the shower. Shower bars touch more of the body and sit wet longer, so many families prefer personal bars there.
5. Use separate soap during illness. When someone in the house is sick, a separate bar or a pump at the sink is a sensible precaution.
6. Keep face bars separate. A small bar dedicated to your face, kept dry, is a tidy habit. Our guide on washing your face with bar soap has more.

When to Be More Careful

If someone in your home has a weakened immune system, open wounds, or a skin infection, follow the advice of their doctor about soap and hygiene. In those situations, single user bars or sealed dispensers may be recommended. For most healthy households, though, a well kept bar is a perfectly sanitary choice, and the habits above take almost no extra time once they become part of your routine.

What About Body Bars Shared by a Family?

Plenty of families share a single shower bar for years without any trouble, and the research above suggests that is reasonable. If sharing bothers you, the simplest answer is a bar for each person, maybe cut from one larger bar, each kept on its own draining dish. Different scents make it easy to tell them apart.

Our Perspective

We make plain, true soap with no antibacterial additives, because soap and water already do the work. Our Body Bar is a good everyday choice for hands and body, and many people keep a separate tea tree and cedarwood Man Bar in the shower for its earthy scent.

From the ranch

Made in small batches, without the ingredients discussed above.

Questions people ask

Can germs live on bar soap?

Yes, bacteria can be found on used bars, especially wet ones in shared settings. Studies that deliberately contaminated soap bars, however, found that those bacteria were not meaningfully transferred to hands during washing.

Is it OK to share bar soap?

For most healthy households, sharing a bar at the sink is considered reasonable. Many families prefer personal bars in the shower, and a separate bar or pump makes sense when someone is sick.

Is liquid soap more hygienic than bar soap?

Liquid soap is preferred in hospitals and public restrooms, where many people share a sink. At home, both bar and liquid soap clean hands well when you scrub for at least 20 seconds and rinse thoroughly.

How do I keep my bar soap clean?

Keep it on a draining dish so it dries between uses, rinse the bar briefly before and after use, and wash the dish regularly to remove soap scum and standing water.

Sources and further reading

1. Heinze JE, Yackovich F, Washing with contaminated bar soap is unlikely to transfer bacteria, Epidemiology and Infection, 1988
2. Centers for Disease Control and Prevention (CDC), Clean Hands: When and How to Wash Your Hands
3. US Food and Drug Administration (FDA), Final rule on safety and effectiveness of consumer antiseptics, 2016
4. World Health Organization (WHO), Guidelines on Hand Hygiene in Health Care

This guide is for general education and is not medical advice. If you have a skin condition, allergy, or are pregnant or nursing, talk with your doctor or a board certified dermatologist about the products that are right for you.