If you’re active in cloth diaper groups on Facebook or elsewhere on the web, then you’ve probably picked up this notion that powdered laundry detergent is supposedly more effective in hard water and liquid is more ideal for softer water. The implied suggestion is that powdered detergents have more softeners added than liquid.
But is this true?
As far as I can tell this suggestion lacks anything more than anecdotal evidence. That is, it’s only been proven based on personal experience, and less on the science of detergents.
They say powdered Tide is good up to 180 PPM and Liquid Tide up to 150 PPM. However, when I approached Tide to ask these questions I was told both detergents are equally effective in water levels and this was not a statement they issued. Tide suggested I might have better cleaning results by increasing detergent in hard water and decreasing in really soft water. They discouraged me from considering additional water softeners, and encouraged me to talk to a Tide specialist if I had extremley hard water. I do not. You can reach out to your laundry detergent manufacturer for more questions.
This is thoroughly disappointing considering the original source for this “knowledge” comes from conversations on Fluff Love University which on its page about soft water washing suggests liquid detergents contain fewer softeners to give you a better washing result.
Research into Detergents
There is very little literature on the topic of the effect of hard water on washing effectiveness of powdered or liquid detergents.
- Abeliotis, K. , Candan, C. , Amberg, C. , Ferri, A. , Osset, M. , Owens, J. and Stamminger, R. (2015). Impact of water hardness on consumers’ perception of laundry washing result in five European countries. International Journal of Consumer Studies, 39: 60-66. Accessed September 2018. doi:10.1111/ijcs.12149
This study was the result of a structured questionnaire in March 2013 to 5 European countries on the discuss laundry issues related to water conditions. The survey resulted in many perceptions about the soft water residents were more satisfied compared to those with hard water challenges. However, very few people used a water softener
The results also indicate that satisfaction on the washing outcome, although reported in high levels, depends on the water hardness. People living in hard water areas are less satisfied compared with those living in soft water areas. Despite the fact that people blame the water hardness for deteriorating the quality of the washed garments, the percentage of people using water softeners is relatively low in all the countries examined. (Albetois, et al., 2015)
- Arai, H. (1966). Study of detergency. I. Effect of the concentration and the kind of detergent in hard water. Journal of the American Oil Chemists Society, 43(5), 312-314. Accessed October 2018
This study looked at the effectiveness of oil removal in hard water. Soiled cotton clothes were placed in Launder-o-Meter with hard water detergent solutions and laundered. Soil removal was measured using reflectiveness. It is suggested as water hardness increases, the concentration of detergent needed to remove oil also increases.
- Brown, D.M., Cameron, B.A., Meyer, S.S. & Umber, J.J. (1991) The effects of water hardness level on washing quality using commercial laundry detergents. Journal of Consumer Studies & Home Economics, 15, 215–222.
Full article unavailable without cost. Sorry, not paying to read it.
Abstract: The water hardnesses were determined for 10 samples of water. A wide variation of water hardnesses were found ranging from very soft to very hard. The effectiveness of six commercial laundry detergents of different formulations were evaluated. The detergent containing a non‐ionic surfactant with a phosphate builder was found to give the best whiteness results, regardless of water hardness. Because of the possible environmental problems associated with the use of phosphates, consumers may wish to select the next most effective detergent formulation, which varied between water samples. (Brown, et al., 1991)
- Cameron, Bruce A. (2011), Detergent Considerations for Consumers: Laundering in Hard Water – How Much Extra Detergent is Required? The Journal of Extension. Accessed October 2018, https://www.joe.org/joe/2011august/rb6.php.
This study looked at the effectiveness of 14 consumer laundry detergents. 6 of these detergents were powder and 8 were liquid, and they were used to clean a soiled cloth in soft and hard water that were then gaged against a whiteness index.
“The results indicate that the liquid detergents were not affected by the increase of the water hardness (no significant difference); however, the powdered detergents were affected. Whiteness indices for the powdered detergents were significantly lower in the 100 ppm hardness water compared to that of the soft water. However, in soft water, the powdered detergents performed significantly better than any of the liquid detergents.” (Cameron, 2011)
Cameron’s results suggest liquid detergent is more effective in hard water because of nonionic surfactants which dissolve better in a variety of water types. Likewise, it’s later suggested that powdered detergent requires up to double or more the detergent to get the cleaning powder of liquid powder which is not economical for many users.
Keiko Gotoh and Yang Mei (2017). Effect of Washing Conditions on Cleaning Action of Linear Alkylbenzene Sulfonate in Hard Water. Tenside Surfactants Detergents: Vol. 54, No. 4, pp. 291-298.
This article is not available without purchase.
From the abstract we can extract this paper tested the water hardness and washing effectiveness using surfactants. They arrived at a few conclusions. Primarily that soft water is the best choice for detergents.
The addition of significant amounts of extra LAS did not fully compensate the reduction in detergency in hard water. Addition of softening agents and an alkali builder to the hard water limited the reduction in detergency, but the detergency was still lower than that in the absence of hardness salts. (Gotoh & Mei, 2017)
If you can help me understand that sentence, you are a godsend. My take is that extra surfactants did not make things more efficient in the hard water, and the addition of water softener limited the cleaning power but cleaning power but it was still better than without.
TL;DR is Powder or Liquid detergent for Hard Water?
Basically, one researcher has come to the conclusion that powdered detergent works more effectively in soft water than hard water.
But, there isn’t any more research supporting this besides the notion that washing in harder water is more difficult, and there are a variety of ways to overcome that.
My conclusion: use whatever detergent you want and see how it works until are able to determine more research into laundry detergent effectiveness between powder and liquid. There’s also an entirely separate conversation to be had about the value associated with powder versus liquid, the environmental impact, and such forth.
Maybe reach out to your local peers and see what they have success with. Find (and if there isn’t one create) a local cloth diaper community and see what everyone else is using. I know what people use here and what they use at my mom’s house is different based on their success with effectively cleaning any laundry.
Stop spreading the myth of powder in hard and liquid in soft because there is very little evidence supporting this, and every brand I’ve emailed has disagreed with that suggestion. Instead own the information you actually know, and cite your sources when you know it.
What’s your experience with laundry detergent and cloth diapers?
Personally, I find powdered Tide the most effective for us. However, I’ve never really tried anything else and I have moderately hard water.
PS I’m totally okay with anecdotal evidence in\ laundry, I just want people to say that.
Just say “in my experience, the powdered detergent is more effective with my water”
Don’t say “powdered detergent is more effective in hard water” <– because there’s no basis on that besides your perceived experience.