Comment by perihelions

I mean, they certainly knew how to make wooden water containers: they wrote it down. This context is dye-making rather than baths,

- "...This water is boiled with an equal quantity of pure water, and is then poured into large wooden reservoirs [original: "piscinas ligneas"]. Across these reservoirs there are a number of immovable beams, to which cords are fastened, and then sunk into the water beneath by means of stones; upon which, a slimy..."

https://www.gutenberg.org/cache/epub/62704/pg62704-images.ht... ("Chalcanthum, or shoemakers’ black: sixteen remedies" (77))

https://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext...