See
https://en.wikipedia.org/wiki/Paris_sewers . Based in those information I'd say that in 1848, Paris' sewer system was at an initial stage only. Therefore, a majority of residents used to remove their waste into gutters (understood as the edge of a road next to the pavement, where rain water collects and flows away - Collins dictionary). Water mentioned in Rosa Luxembourg's text could be a mix of waste water and rain water (depending on precipitation at that particular time of the year).
Polish word "rynsztok" (= EN "gutter" as in Collins) includes the "sztok" group of characters that I dare to associate with "stok" and "stoczny".
Still, that's an amateur etymology only and I may be wrong. ;-)