The joys of Bath
The Georgians might not have had a germ theory, but there was certainly some sense of it, as this lively description of the circumstances in Bath describes ... (Not recommended if you are eating.)
But I am now much afraid of drinking as of bathing ; for, after a conversation with the doctor, about the construction of pump and the cistern, it is very far from being clear that the patients in the Pump Room don't swallow scourings of the bathers. I can't help suspecting that there is, or may be, some regurgitation from the bath into the cistern of the pump. In that case, what a delicate beverage is every day quaffed by the drinkers! medicated with the sweat, and dirt, and dandruff, and the abominable discharges of various kinds, from twenty different diseased bodies parboiling in the kettle below. In order to avoid this filthy composition, I had recourse to the spring that supplies the private baths on the Abbey Green ; but I at once perceived something extraordinary in the taste and smell: and, upon inquiry, I find that the Roman baths in this quarter were found covered by an old burying-ground belonging the abbey ; through which, in all probability, the waters drains in its passage : so that as we drink the decoction of living bodies at the Pump Room, we swallow the strainings of rotten bones and carcasses at the private bath.
This is from The Expedition of Humphry Clinker by Tobias Smollett (1772); the speaker, or rather writer, since this is an epistolary novel, the glorious misathropic Matthew Bramble, a middle-aged hypochondriac.
There's a short account of the novel here and the ebook.
(This from Hutchinson & Co 1901 edition, p. 62)