There was an interesting article in yesterday’s Guardian which bears out something I have long thought. It begins …

I shower once a week. Here’s why you should too.
Daily showering is expensive, polluting and unnecessary. The old-school weekly bath or shower — with a brief daily sink-wash — is healthier for the environment, and for us.
When I was a kid, bathtime was a once-a-week affair. We weren’t an unhygienic family — this is just how most of us lived in the 1960s, and I do not remember any horrific body odours resulting from it. By the time I was an adult, I was showering every day. With hindsight, I should have stuck to the old ways.

Indeed so, although in my family bathtime was twice a week, at least for me. If nothing else heating water was inconvenient and expensive in the days before ubiquitous central heating.
As a student I did shower every morning, and often more than once a day as I was playing lots of cricket, squash etc. Otherwise I actually have stuck to my childhood regime. Although it’s a bit more flexible now (partly down to lifestyle and partly as there’s easy hot water) I seldom shower more than a couple of times a week. And even then one seldom needs to spend more than 5 minutes in the shower (according to the article the average shower lasts 10 minutes).
(Now I’m not working, I also seldom shave more than every few days. I can’t stand more than 5 or 6 days beard, but shaving every day gives me far more skin problems.)
Did anyone notice? No of course you didn’t. Most of us don’t lead very dirty lives. Few these days work in dirty industry, down the mines or shovelling muck on the farm — when I concede that a daily bath or shower, after work, would be essential.
Yes, I like that nice, clean, scrubbed and pampered feeling a shower gives you; especially if you can then dive under lovely crisp, fresh bed-linen. It’s pleasant. But it isn’t essential. And on its own it isn’t a good reason for a daily shower (or two).
This is one area where we could go back in time without actually feeling any inconvenience. It would save massive amounts of water; and you would save on the cost of heating that water — both of which would be good for the environment as well as your wallet. On top of which you would probably save some time; and it might actually be better for your skin. That sounds like WIN-WIN to me!
Oh and here’s another take on the question from a plumbing supplier.