Hacker News new | ask | show | jobs
by OnACoffeeBreak 2340 days ago
Obviously you don't feel that using cold water negatively impacts how effectively you can clean yourself otherwise you wouldn't do this, but I was interested to know because I assumed hot water is better. So, I did some searching, and results appear inconclusive [1]:

> The impact of handwashing techniques on infectious diseases among the general public in community settings has not been extensively studied.Hot water for handwashing has not been proven to have an added anti-microbial effect.

1: https://www.academia.edu/20383485/Hot_Water_for_Handwashing_...

5 comments

It certainly discourages lingering in the shower. When I was doing it (cold tap open, no hot water at all, Michigan, winter) when that water hit you you definitely moved quickly. With hot showers 20 minutes isn't uncommon if I'm tired and enjoying the hot water in the winter. With cold showers...5 minutes from turning on the faucet to hopping out. I never noticed any reduction in my cleanliness, but what I absolutely noticed was an improvement in my skin. Hot showers in a dry environment like a Michigan winter leads to very dry and cracked skin. With cold showers my skin was in much better shape. No cracking, no flaking.
Yes, good to know as it's quite a usual counter-point I get. The differences are trivial in my opinion.

I take about two showers a day, mainly because I do sports, so I think I make up with the volume ... even training in sometimes dodgy gyms around the world or doing jiu-jitsu for a long time basically rolling on the ground with sweaty dudes, I was able to keep myself clean of any infections, fungal or viral ... I'm just taking regular shower clean myself properly, the the body should fend off easily.

It's anecdotal but I think doing hygiene properly and regularly makes bigger impact than temperature of a water.

Cold showers after jiu jitsu on a hot day are like being in heaven for a moment.
I wouldn't expect hot water to have a significant effect. In cooking, you need to hit 140F to kill bacteria, which would be extremely unpleasant. It's literally scalding; you can get second and even third degree burns in seconds. Pleasantly-hot shower temperature is in the "danger zone" for food handling, where bacteria grow faster.

Using soap will kill bacteria, and as long as the water is warm enough for the soap to foam up, that's going to do all of the work. Adding more heat will just make things easier on bacteria.

Interesting. Pure speculation but if the shower were very cold could that lead to shorter cleaning times too (not that I ever left "unwashed", but I recall when my boiler failed I was super-speedy showering!)
Heat means more energy which means more movement of particles. More movement of particles, especially where soap has decreased surface tension of water, means water touches and helps carry away more dirt and other removable particles.