Sewers/toilets in middle earth?

[Lalwendë]

Just had a quick look at the entry on Tanning on Wikipedia and both urine and dung were used in the process of tanning leather.

Once the hair was removed, the tanners would bate the material by pounding dung into the skin or soaking the skin in a solution of animal brains. Among the kinds of dung commonly used were that of dogs or pigeons. Sometimes the dung was mixed with water in a large vat, and the prepared skins were kneaded in the dung water until they became supple, but not too soft. The ancient tanner might use his bare feet to knead the skins in the dung water, and the kneading could last two or three hours.

It was this combination of urine, animal feces and decaying flesh that made ancient tanneries so odiferous.[citation needed]

Children employed as dung gatherers were a common sight in ancient cities. Also common were "****-pots" located on street corners, where human urine could be collected for use in tanneries or by washerwomen. In some variations of the process, cedar oil, alum or tannin were applied to the skin as a tanning agent. As the skin was stretched, it would lose moisture and absorb the agent.

Ew.

Given that leather must have been a product in very high demand in Middle-earth ( for clothing, shoes, saddlery and of course armour), there must have been lots of tanneries (and lots of cows and meat) so it makes you wonder were there urine collectors in Minas Tirith etc.

Elves used lots of leather, too. It alters your image of them somewhat to imagine them collecting urine and dung and them stomping around in vats of it for hours on end.