“No brother may bathe, let blood, take medicine, go into town or ride a horse at a gallop without permission; and wherever he may not go without permission he should not send his squire or his horse without permission. (The Rule of the Templars, ch. 144, pg. 55)

It certainly seems to be true that the Templar rule prohibits bathing! But as usual the answer is actually much more fun than that. What does the rule really mean here?

First of all, u/BRIStoneman has a lot of previous answers to give you a good background on medieval bathing:

Were European medieval hygiene habits and beliefs really as terrible as we’ve been commonly led to believe, or were they, at least in some cases, better than most would think?

Conflicting information on medieval bathing

[What was the reason for the decline of basic hygiene from the Roman empire to the Middle ages in general?](https://www.reddit.com/r/AskHistorians/comments/bqjfh7/what_was_the_reason_for_the_decline_of_basic/eo83nt6/)

Dirty Medieval Peasants

The other thing to keep in mind is that the Templar rule is based on older rules for monastic orders, going back hundreds of years earlier to the period of late antiquity/the early Middle Ages. The Templar rule was based on the Cistercian rule, which was developed at the Abbey of Citeaux in northern France in the 11th century, as an attempt to reform the Benedictine rule. The Benedictine rule was written by the Italian monk Benedict of Nursia in the 6th century, and was one of the major early medieval monastic rules in Western Europe, along with the Augustinian rule written by Augustine of Hippo in the 5th century.

When Benedict and Augustine talk about bathing, they’re thinking of the Roman style baths of their own era. Public baths had a reputation both for being sort of luxurious, a place you could go to get pampered; but also for being very shady, places where criminals might gather and especially somewhere you would probably find prostitutes. Monastic rules promoted an ascetic lifestyle, where monks weren’t supposed to care too much about their appearance or indulge in food or drink, and sometimes they weren’t even allowed to talk, among other things. They were supposed to dedicate themselves to prayer and study. Regular bathing might suggest they were too concerned with their physical body instead of with their soul, and by visiting a Roman-style public bath they might be introduced to too many earthly temptations.

But the early medieval monastic rules weren’t completely opposed to bathing. The sick, especially, are instructed to visit the baths:

“The sick should be granted the use of the baths as often as it seems useful, but they should be allowed less readily to the healthy, and especially to the young.” (Rule of St. Benedict, ch. 36, pg. 300)

The Augustinian rule also notes that monks should go to the baths in groups so they don’t fall into temptation while they're alone. They should also go with monks they don’t know rather than their friends - the implication seems to be that the baths might be a place for homosexual liaisons between monks, in addition to other possible sexual encounters.

Benedict and Augustine came from the highly urbanized areas of Roman Italy and North Africa where there were plenty of baths, but further north, where the climate was different, there were fewer people, and the environment was much more rural than urban, there wasn’t much of an ancient Roman bath culture. As explained in BRIStoneman’s answers above, medieval people who didn’t have (or who no longer had) access to Roman baths certainly still understood hygiene and cleanliness, and they still bathed in other ways, in lakes or rivers for example. In 11th-century Citeaux there weren’t any Roman baths, but the Cistercians emphasized Benedict’s asceticism, so monks weren’t encouraged to bathe too frequently.

This applied to the Templars too, as an offshoot of the Cistercians, but in the crusader states where the order was founded and where they had their headquarters, there was still an urban environment and an ancient bath culture. Crusaders from Europe who had never experienced public baths before quickly became accustomed to them. There’s a funny story by the Damascene poet Usama ibn Munqidh about a crusader knight and his wife who discover the concept of shaving their pubic hair at the public baths (I wrote about that story here). So when we read about Templars using or not using the baths, this probably does, once again, refer to Roman-style bathing.

But we should also re-read the actual statement in the Templar rule. It doesn’t really say the monks aren’t allowed to bathe at all, just that they aren’t allowed to do so without the permission of their commander. It really refers to the entire Templar lifestyle - all Templars were supposed to be treated the same, regardless of how rich or poor they were when they joined. They had to follow a strict chain of command and everything about their life was rigidly structured). So the rule is actually talking about obedience and deference to authority, not really bathing specifically.

In short, monks and other people continued to bath, but monastic life was supposed to focus on spirituality rather than the physical body. Public baths were a notorious place for the sort of temptations monks were trying to avoid, so they shouldn’t go there too often. Templar knights were very familiar with public baths in the eastern Mediterranean and they probably weren’t supposed to go there often either. But the rule doesn’t forbid bathing in general, it simply refers to following the instructions of the Templar master (or a local commander).

Sources:

Malcolm Barber, The New Knighthood: A History of the Order of the Temple (Cambridge University Press, 1995)

Malcolm Barber and Keith Bate, The Templars: Selected Sources (Manchester University Press, 2007)

J.M. Upton-Ward, The Rule of the Templars: The French Text of the Rule of the Order of Knights Templar (Boydell Press, 1992)

Terrence G. Kardong, Benedict's Rule: A Translation and Commentary (Liturgical Press, 1996)

Janet Burton and Julie Kerr, The Cistercians in the Middle Ages (Boydell, 2011)