My dad grew up in the coal mining district of Chesterfield, England. In those days the English washed once a week. We heard a story of one family with 9 children, and they all used to bathe in the same water, starting with the least dirty person and ending with the dirtiest. The father, being a coal miner was of course, the dirtiest, and was washed last, even after the dog!!!
Things may have changed for some of us since then, but when I was in Kathmandu the water was only turned on for an hour a day. That's when you washed (yourself, your clothes, the dishes), flushed the toilet and filled a bucket of water for later. In some African tribes, where water is even more scarce, they wash in smoke from the fire.
Bathing is an interesting thing. Everyone, every where in the world does it and we all do it differently. Here's a little something about Ayurveda's views on bathing.
"Soap is not meant for use on the body except when it is really grimy, and even then, as modern medicine agrees, it should never be used on the mucous membranes...
Bathing is prohibited within an hour after eating, and when one is suffering from accute diarrhoea, abdominal distention, chronic cold, indigestion and most acute illnesses. The yogis always advise cold water for bathing, while Ayurveda suggests hot water, except on the head, where only warm water should be used lest it weaken the sense organs."
Ayurveda; Life, Health and Longevity, Robert Svoboda.
Bathing should be done before meditation, prayers or sex. If you want to avoid soap you can use beans. It can also be useful to bathe with salts, oils or essential oils depending on your condition.