Plumbing

[Urtx13]

Some of the outlets on tubs can be compared to spouts of wells or fountains.

In fact most of the structures that have nymphs inside can be related to well imagery (look for Joseph in the Well, Fountain of Life etc). This is not a mainstream opinion though, I think most people like the idea of bathing and plumbing.

This is a fascinating perspective. The idea of well and fountain imagery fits nicely, especially with the spout-like outlets you mention. It makes me wonder if the nymphs could represent spirits of wells or some kind of water personifications. 

It reminds me of some folkloric traditions: for example, in my region, Catalonia, Spain, there is a figure called the Dona d’Aigua (“Water Woman”), a mythical spirit associated with natural springs and wells. This makes me wonder if the nymphs in the manuscript could represent something similar, spirits of water sources, fertility symbols, or guardians of wells.

Soooo cool!