Most people are under the impression that washing your hands in hot water is more beneficial than washing with cold water. This may be because we are under the impression that hot water sterilizes and cleans betters.
Researchers at Vanderbilt University conducted a study demonstrating that there are few, if any, benefits to using warm water in comparison to cold water to wash hands. They found that in order for water temperature to make a difference, it must be past a degree that is safe for human contact. Hot water is a powerful skin irritant that can cause dryness, burns, and other skin conditions. Soap is what actually kills bacteria and cleans your hands, rather than water.
Aside from hot water being unnecessary for hygiene, it also has substantial environmental impacts. Lowering hot water use can reduce annual heat trapping (greenhouse) gas emissions and fight climate change.
Residential water heating, including boilers, radiators, and gas, are responsible for a large sum of carbon emissions into the environment. According to these researchers, handwashing alone accounts for over six million metric tons of carbon dioxide emissions annually.
Though, in scope, hand washing habits may not seem to have a large impact, switching from hot water to a comfortable temperature can aid in lowering our carbon footprint.
This article references an article from Vanderbilt, found here.