12th Century bathing
There are many manuscript illustrations of wooden tubs, sometimes with fires underneath them (possibly the tubs with fires underneath aren't wooden). The tubs generally appear to be half barrels which are taller than they are wide, and are usually depicted as fairly narrow - just wide enough for a person to sit on a stool in, and tall enough to reach their chest seated. Apparently such barrels in private homes of the nobility could serve as a base for a table in between uses. 
Holmes cites a romance with a girl who bathes in the household vivarium (an artificial fish pond in courtyard or kitchen to store fresh caught live fish until eating), wearing only her shirt, on hot days. It was considered fairly shocking that she did so in front of males.
In the lay Graelant a maiden is bathing naked (old French: Qui en la fontaine esoit nue. - Who was naked in the pool). Her chemise is noted as being in the pile of removed clothes. However there are elements that show this is a fairy maiden, so her behaviour is not necessarily that of a proper noble lady.
The [Wikipedia:Holy_Roman_Emperor|Holy Roman Emperor] [Wikipedia:Frederick_I%2C_Holy_Roman_Emperor|Freidrick Barbarossa] drowning while stopping at a river to bathe on route to the Crusades. It is likely that men of all ranks would use natural water sources to clean themselves in warmer weather. Nobles may well have worn their shirt when doing so, indeed it may have been a good time to clean the underwear too.
It is possible to clean all of one's body quite well using a basin of warm water and a cloth, and preferably some soap. This is aided if during the day most of the body has been covered from dirt by clothing, for example veils of hats covering the head, long sleeves and long shirts or pants.
The advantage of such a wash is that it uses little water, and can be performed very quickly - a huge advantage in cold weather.
We have no evidence that such a method of cleaning was used in the 12th Century, but it seems likely given the limited frequency of full tub bathing.
There is quite a ritual of washing the hands before a feast. Romances talk of the ritual for welcoming a knight, after travel or hunting. Before the feast begins he is presented a basin of water and a towel to wash his hands. Holmes suggests water might be poured from a pitcher, over the hands, into the basin and that soap might be offered as an occasional luxury, but not everywhere.
There are also big wash basins in romanesque monastaries so the monks could perform this ritual washing before eating. 
Rather strict hygene rules that operate while eating or preparing food - not so much washing as not touching the nose or mouth, using the correct hand etc. Such rituals would make frequent hand washing less important.
In 12th C towns such as London and Paris, bath keepers kept public baths, where the general public could bathe (in the barrels mentioned above), but this does not appear to be a daily ritual. 
Bathing was required as part of a vigil prior to a knighting.
The season of bloodletting for monks was a season of bathing and relaxation.