The SDA (Soap and Detergent Association) logically states: “To understand what is needed to achieve effective cleaning, it is helpful to have a basic knowledge of the soap and detergent chemistry.”(1) Now, this isn’t going to be a lesson in Chemistry – hopefully, you’ve already made that rite of passage in high school and/or college, BUT we do want to give you a bit of basic knowledge regarding the difference between soaps and detergents. We get many questions regarding what to use for laundering cloth diapers – well, read the following article and hopefully it can equip you in making that choice for your family’s laundry.

First things first – a lesson on surfactants. I know, you are saying, “Sur-what?” Surfactants, also called surface active agents are the chemicals necessary to reduce the surface tension of water. What that means (basically) is that water will hold to itself because each water molecule is surrounded by and attracted to other water molecules. This property of tension with water causes it to bead-up on surfaces like fabric (you know, like a drop of water on a counter . . . it does not spread-out, but beads up instead) and will slow the wetting of that surface – which inhibits the whole cleaning process. . In order for the water to spread and wet/soak into a surface (like your laundry) – you need surfactants, chemicals that effectively cut the surface tension and are said to “make water wetter.” (1) So, the first commonality between soaps and detergents, even though they are not exactly the same thing, is that they are both surfactants. “Any surfactant that is not a soap is a detergent.” (2)

Both soaps and detergents perform the same task. – As far as removing dirt or poopies (since we are specifically concerned about getting your diapers clean), the difference between soaps and detergents are in their composition. Soaps, on the whole, are made of materials found in nature, and detergents are labeled synthetic (although some of their ingredients are natural). (3) An interesting point is that some chemists will argue that the actual production of a soap molecule from the naturally occurring fats and oils is still a synthesis step, and therefore, soaps are synthetic products as well. (2) The EPA states, “The word ‘detergent’ refers to household cleaning products which are based on non-soap, synthetic surfactants and which are primarily used for laundering and dishwashing.”(5) Whichever side of that argument you lean on, we do recognize that soaps have been around for centuries and that they are better overall for our health and easier on our environment than detergents.


So why the production of detergents if soaps are tried and true? Well, there is one big drawback in soaps that seemingly pushed the detergent industry, and that ‘drawback’ is the principal difference recognized between soaps and detergents. Soaps and detergents behave differently in hard water. Soaps form a scum in hard water and this scum will not rinse away easily and is known to turn laundry a grayish hue. The insoluble film it leaves can leave a residue on your laundry much like you would see in a shower stall where hard water is present. Detergents react less to minerals in water and do not leave this residue. (3) If you live in an area where the water is soft, you will have more success with soaps, but even then a gradual build-up of calcium and magnesium ions (also called ‘curd’) will be left in the fabric of your diapers or any of your family’s laundry over time. Another disadvantage cited with soaps is that they “ . . .will deteriorate in storage and lack the cleaning power when compared with the modern synthetic surfactants.“(4) Because of this, detergents have steadily become the cleaning agent of choice since World War II, because for all practical purposes – synthetic or not, they will leave your laundry cleaner.

Those concerned about the environmental effects of soaps and detergents do have options. Since both soaps and detergents are surfactant based, you can make the effort to choose a product whose surfactants are made from oleochemicals, instead of those made from petrochemicals. Petrochemicals are a nonrenewable resource and actually a ‘waste product’ of the petroleum industry derived from crude oil or natural gas. (1,4) Oleochemicals are from fats and oils, which are renewable resources.

As we mentioned earlier, the surfactant raw materials of both soaps and detergents must be chemically converted. That being the case, in its final form, the surfactant with an oleochemical base is similar to one with a petrochemical base. (1) The obvious question then is why do manufacturers choose to use a non-renewable petrochemical when there is another option – oleochemicals. Well, primarily ‘cost.’

We recommend the use of detergents with regards to washing cloth diapers. Obviously, finding a detergent that is environmentally-friendly isn’t easy, but for our diapers’ longevity, we prefer to stay away from the build-up that would detract from the diaper’s maximum absorption capabilities. We also want our diapers to have every opportunity to get completely clean – and with a build-up, we feel that isn’t possible over time. Because we are asked so often, we will tell you that we have used Arm & Hammer Detergent (liquid/without bleach), however, because of the less than satisfactory Phosphate content in the Arm & Hammer, we began sampling other detergents as well. To our surprise, we have found that some of the groceries’ generic brands are more environmentally sound than a good portion of their name-brands.

What you should look for is a product that is Phosphate Free or low (containing trace amounts) in Phosphate, Fragrance and Dye Free and does not contain Fabric Softeners. With regards to our bodies, we use all natural soaps – we particularly love Dr. Bronner’s Castile Soaps!

One note of caution. There is a misconception that all products labeled environmentally safe are ‘safe’ across the line – and that just isn’t true.  Detergents are responsible for many household poisonings according to the EPA (Environmental Protection Agency).  “Part of the problem is that detergent boxes are brightly colored and attractive and commonly stored in low, accessible places . . . while low phosphate detergents are safer to the environment, they are 100 to 1000 times more caustic than phosphate detergents.” (5) In other words, they can cause serious burns even if only a small amount is digested.  In homes with young children, powder (rather than liquid) detergents are recommended because it is more difficult to swallow powder granules.  Please, if you have small children, keep the detergents stored well OUT OF REACH.


  1. SDA – The Soap and Detergent Association, Chemistry.
  2. What is Soap? What is a Detergent?
  3. The Difference Between a Detergent and a Soap.
  4. Synthetic Surfactant or Soap?
  5. United States Environmental Protection Agency. Great Lakes National Program Office. Detergent.


© 2002, Heather L. Sanders. May not be reprinted without permission.

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1 Comment on Soap vs. Detergent

  1. Christian says:

    Surfactant detail was a nice one,please i want to know the types of surfactant

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