I found these foaming soap dispensers on Amazon.

The seller says you can use regular liquid soap, diluted:

Combine 1 part liquid soap with 5 parts water or Fill with foaming soap solution / Castle Liquid Soap.

You use less soap per wash.

Foaming soap dispensers release less soap than regular liquid soap dispensers do, allowing users to achieve the same level of cleanliness with less soap. Less soap per hand wash makes the same amount last longer, which costs less.

Is the reduced amount of liquid soap (diluted and foamed) as effective as regular liquid soap?

  • I don't believe it the seller is saying that the soap needs to be diluted with later before adding to the dispenser. They are saying that the resultant foam is less concentrated (diluted with air bubbles) than regular soap. Edited to match the claim.
    – Oddthinking
    Commented Jul 7, 2016 at 14:23
  • In a consumer behavior course, we studied people's tendency to overuse liquid laundry soap when it is especially condensed. We didn't study hand soap, but perhaps the concentration to volume given per pump ratio leads to over use. I know my kids certainly overuse by about three times what they need.
    – user11643
    Commented Jul 7, 2016 at 16:45
  • I don't think this can be objectively answered, since the amount of soap needed to clean depends on how much dirt is being removed.
    – Flimzy
    Commented Jul 8, 2016 at 8:01
  • 1
    @fredsbend: I am hoping that there will be a consumer behaviour study that will address this.
    – Oddthinking
    Commented Jul 8, 2016 at 15:28
  • 1
    @Oddthinking You do dilute the soap before adding it--the foam dispensers need a thinner liquid than normal liquid soap. However, this doesn't mean it's less effective because in normal hand washing you dilute it anyway by wetting your hands first. Commented Jul 9, 2016 at 4:00


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