Is Cold Water Effective for Washing Hands?
I don’t know about you, but I always thought that you had to use warm water to kill germs when washing your hands. At All Portable Sinks we have learned a lot over the years about the science of hand washing and the importance of using effective techniques. One of the surprises for me was to learn that cold water is just as effective as warm or “hot” water for washing hands because it’s the friction and time that does most of the work. Do you find that hard to believe? Here’s some of the science behind hand washing that explains why cold water sinks can be just as effective when you are adding portable hand washing stations to your business or school.
The recent pandemic has made us all more aware of the importance of practicing proper hand washing techniques so we can reduce the spread of viruses. There has been a resurgence of info-graphics and posters reminding us to wet our hands, apply soap, lather and then scrub our hands (including fingers and nails) for at least 20 seconds before rinsing and drying.
For years, it was assumed that warm (or reasonably hot) water was best for washing hands but the efficacy of water temperature on killing microbes was not tested that often. When it has been tested, the research consistently shows that the temperature of the water is not a factor in the efficacy of washing hands. In a study conducted by Micheals et al. in 2002 to specifically test if the temperature of the water made a difference in destroying bacteria and microbes, they found that cold water was just as effective. You can read more on this scientific study here.
The CDC (Center for Disease Control) states on their website that when washing hands with proper technique, "The temperature of the water does not appear to affect microbe removal..” They do state that the water should be flowing to avoid contaminated stagnant water and you should wet your hands, turn off the running water source while scrubbing with soap, then turn water back on again to rinse. This conserves water and energy.
Cold Water Hand Washing Can Help The Environment
In a study by Carrico, A. et al. on the environmental cost of warm water hand washing, they list several scientific studies done on water temperature and emphasize that fact that despite scientific evidence suggesting the temperature of hand washing does not make a difference, people continue to believe that warm water is better. Their study focused on this pervasive belief and how using cold water only for hand washing could have a positive impact on the environment by reducing the energy used heating water.
Why People Prefer Warm Water
The first reason people continue to believe that warm water is better is because of the belief heat is needed to kill bacteria. In the Carrico et al study it says: “Despite what is commonly advocated, there are no known data to support the claim that water temperature is associated with h.and washing efficacy. It is true that heat kills bacteria; however, the level of heat required to neutralize pathogens is beyond what is considered safe for prolonged human contact.” Many pathogens need a prolonged temperature of 130-140°F to be killed which would be dangerous for human hands. The typical warm or “hot” tap water is not warm enough to have any significant advantage over cold water in killing microbes or reducing pathogens. It is the combination of water, soap, friction with proper technique, rinsing and then drying hands that is effective in the spread of disease.
The second reason people tend to believe that warm water is better according to this study is comfort. People associate warm water with cleanliness and comfort in many cultures, especially in western cultures like the United States and Canada therefore they “feel” better about washing their hands in warm water, even though scientifically there is no known advantage because the water does not get hot enough to kill pathogens as stated above. Hot water is useful in sanitizing dishes and utensils because the temperature is much higher in those applications than what is recommended for human skin to avoid damage.
Why It's Good to Offer Warm and Hot Water Sinks
At All Portable Sinks we sell both warm and cold water sinks because we want to offer options so consumers feel comfortable and we want to help businesses meet regulations. If people feel better and more comfortable washing their hands in warm water, they will wash more often. Our goal is to increase hand washing access to help businesses and schools reduce the spread of germs and disease. A hot and cold water sink will allow the user to decide whether cold or warm water is preferred.
We also know that many government agencies and regulatory organizations require facilities to have sinks that have water at specific temperatures. Health codes and food related industries also require hot water sinks. Schools, retailers and businesses have to meet rules and regulations set by municipalities and offering both hot and cold water may be required. Before purchasing a sink, we always recommend that you check with your local authorities to understand their requirements. As with any plumbed sink, you can always just use the cold water which may reduce the use of energy needed to heat the water plus be just as effective in reducing the spread of germs if hands are washed properly.
It’s All In The Process
So how does cold water hand washing remove germs and reduce the spread of disease?
Now that you know that temperature is not a factor in the efficacy of hand washing, it’s important to review what is effective. The CDC website along with many other governmental agencies and organizations recommend using running water and soap when available. The CDC website states that “surfactants in soap lift soil and microbes from skin, and people tend to scrub hands more thoroughly when using soap..” They do not find that the use of antibacterial soaps make a significant difference. A study by Burton, M. et al. concluded that washing with soap was more effective at the “removal of bacteria of potential fecal origin from hands than handwashing with water alone" and recommended the use of soap to reduce the transmission of bacteria and some potential diseases.
After you wet your hands and dispense soap into them, it’s using the proper technique for enough time that makes the difference in how many microbes are removed. The recommended time based on research varies between 15-30 seconds and most, including the CDC, recommend at least 20 seconds.
It’s important that while rubbing your hands with soap you scrub both the tops and bottoms as well as the wrists. Also rub soap in between fingers, around finger tips allowing some of the soap to be rubbed on and under the fingernail. Following this procedure for the full 20 seconds (“Happy Birthday” sung twice or the Alphabet song with ending) will create enough friction to release the germs you can then rinse off.
Cold Water Portable Sinks
Cold water portable sinks can save you money and resources. We have cold water sinks that still use an electric pump for water flow as well as portable sinks that operate without electricity using a foot or hand pump. If your local, state and professional governing regulations allow cold water sinks, it may be a good option if you need to add more hand washing stations.
Jonti-Craft has two cold water sinks that are identical to their popular selling warm water models except for the fact that they do not have a water heater. The Clean Hands Helper 38” Cold Water Portable Sink is an adult height sink and their newest cold water sink, the Clean Hands Helper 26” Cold Water Portable Sink is a child height portable sink. Both of these models can be purchased with a touch-free faucet adapter to make the sink even more effective at reducing the spread of germs by operating hands-free with an automatic sensor to turn on the faucet.
We also offer a few other cold water only sinks that you can see in our Cold Water Portable Sink collection here, including the Monsam Foot Pump Portable Sink with Cold Water Only that operates using a foot pump, perfect for outdoor use.
Reviewing the science behind hand washing is always a good reminder for us to focus on the technique and time needed for effective hand washing rather than the water temperature so we can do our part in reducing the spread of germs and disease.
If you need to add a portable hand washing sink feel free to contact us via live chat, by email or phone.
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