Gurtturs is an archaic spelling of the modern day word, “gutter.”

A modern day gurttur or "gutter"

Things, such as water or possible faecaes (mod: feces) would pass through these unintelligible series of metal tubes.

Note that “gurtturs” is both the singular and plural form of the word as the word was coined long before the word “plural” was formed. Usage is believed to be similar to the following:

Or, in the plural form,