If you're like most people, the answer is probably less than 24 hours ago.
There's no official protocol for how often to shower, but folks around the world — in countries like India, the US, Spain, and Mexico — all bathe about once a day (either with soap or without), according to Euromonitor International.
On Reddit’s ‘AskAnAmerican’ channel, top commenters in the US say they shower even more than that — up to twice a day, depending on how often they exercise. And in Brazil, where temperatures in some areas soar in the summer, some rinse more than 11 times every week, Euromonitor says.
But are frequent suds really necessary?
The American Academy of Dermatology gives parents advice about how often to bathe their kids, based on how dirty and smelly they get. If they’re not too dirty from playing, the recommendation is a bath at least once or twice a week for kids between the ages of six and 11. Their little developing immune systems need some dirt (organisms like bacteria and small doses of viruses and infections) in order to grow up strong.
But once we hit age 12, the official bathing guidance stops. The AAD seems to assume that just about everyone is trying to wash away those awkward teenage smells, and that most people have a daily shower routine by the time they've reached puberty.
The truth is that we probably don't have to shower that much.
Soap is built to pull dirt and oil off the skin and wash it away. The science of this sudsy magic is based on a two-part formula: a combination of either fat or oil plus an alkaline substance that dissolves in water (like salt or baking soda). The two ends of the soap molecule work together to pull grease and oil off of skin (or clothes, or pots and pans) and into the water.
When the loss of natural oil is combined with harsh scrubbing and scalding water, a long, hot, soapy shower can become a recipe for dry skin. This is especially true in the winter, when air is drier both indoors and out.
And skin damage from the shower doesn’t stop when you turn off the water, according to David Leffell, author of "Total Skin: The Definitive Guide to Whole Skin Care For Life" and chief of dermatologic surgery at Yale School of Medicine.
Leffell told Business Insider that as a bather steps out of the shower and dries off with a towel, additional moisture left on the surface of their skin gets lost in evaporation.
In other words, top layers of moisture are being “pulled from your skin” as you exit the shower, Leffell says. Unfortunately for those who love a piping-hot shower, the hotter the water is, the worse this moisture-sucking phenomenon gets, since warm water evaporates even faster than cool.
Leffell offered three pieces of advice for a skin-friendly shower:
He said you can usually get rid of the most offensive body grime in under three minutes by focusing on the armpits and the groin, while not overdoing it with soap on the other (less fragrant) parts of the body.
“You don’t want to do the Lady Macbeth thing where you’re scrubbing and scrubbing,” Leffell said. “The purpose of showering is to eliminate dirt.”
And while some people swear by an invigorating 'cold blast' at the end of a shower, Leffell said you can skip that part, since it doesn’t have any lasting impact on skin health.
The bottom line? No one's going to tell you what to do in the privacy of your own bathroom, or determine which regimen is best in your own shower. If a daily rinse feels like the best part of waking up, then just keep it short and follow up with a moisturizing routine.
But every other day is probably plenty often, as long as it doesn't lead to poor sniff test reviews from those closest to you. If you're just popping in to the water on the daily because it feels like the 'right' thing to do, then feel free to skip some of those showers and get on with your life.