Bar Soap vs. Liquid Soap: Which Is Actually More Hygienic?

Bar soap or liquid soap, which one really cleans better? According to public health experts and professional cleaners, the answer isn't as clear-cut as you might think.

There’s a longstanding debate between bar soap and liquid soap, which one cleans more, which one is safer. According to the CDC and FDA, both are effective for routine handwashing. The difference lies in how each one can be contaminated.

Being exposed and handled when washing, bar soap is easily contaminated with bacteria through its surface. A study back in 1984 found that 92 to 96 percent of samples taken from bar soap contained detectable bacteria, compared to just 8 percent of liquid soap samples.

But experts say the bacteria found in bar soaps isn't necessarily the bacteria that can be passed on to another person, or that can make you sick. "Bacteria on the surface of a bar doesn't automatically mean those bacteria are transferred to the person using it," says Dr. Janis Kosma-Covey, a compounding pharmacist and skincare formulator.

She cites a study where bar soaps were deliberately contaminated with high levels of E. coli and Pseudomonas aeruginosa. After participants washed their hands with the contaminated bars, researchers didn't detect either bacteria on their hands.

The key is in how the bar soaps are stored, according to Dr. Steven Goldberg, a board-certified physician. "Standing moisture is what allows organisms to survive," says Goldberg, so it’s safer to use a soap dish with holes for drainage, keep the bar away from direct water spray or contact, and rinse it regularly to avoid the growth of bacteria on its surface.

This is not to say that liquid soap cannot be contaminated. The risk, according to the CDC, is in refilling dispensers without fully emptying and cleaning them first. This is what can cause bacterial growth. Sealed, cartridge-style dispensers are recommended to reduce the risk.

For practical reasons, most professional cleaners opt for liquid soap. "With liquid soap, there's no shared bar being handled by everyone," says Kathy Turley, a professional cleaner and marketing director at Home Clean Heroes. Cleaners also prefer liquid soaps, which tend to look tidier on a countertop, as opposed to bar soap which often leaves a residue on dishes and sinks, requiring regular scrubbing.

However, cost-conscious cleaning experts prefer bar soaps. Aside from being affordable, it’s more eco-friendly, especially for single-person households where the bar soap isn’t shared with anyone else and hygiene isn’t a problem.

Long story short, when it comes to actual hygiene, the science suggests both are equally hygienic, as long as they’re used and stored properly. More importantly, it’s the washing technique that matters. Experts recommend 20 seconds of scrubbing with soap and clean running water before rinsing and drying.