Paris' sewer system was pretty stagnant, developmentally, between the installation of underground sewage channels under Rue Montmarte in the 1370s, and Haussman's new system by the 1850s (Mt. Holyoke). Expansion was slow and costly, and the infrastructure was frequently crumbling. Building materials were sometimes sourced from Roman aqueduct ruins, as elsewhere in Europe.

Paris' fresh water sources came by aqueduct or canal.

As for bathing and hygiene, the Seine, despite being essentially an open sewer, would host bathers in the warmer months. There were bathhouses, some more elaborate than others,

But those baths charged a fee. The poor were left with the option of bathing directly in the Seine, or not at all. In any case, they washed their clothes in the river.

The rich might source their drinking water from outside the contaminated city, whereas the poor would drink low-quality fermented beverages. And everybody drank wine or other fermented liquids. Here are some interesting excerpts from an author's blog on the Seine and Paris sanitation:

“Some say it loosens your bowels, but I drink it everyday, and I’ve never suffered anything like that. But then I let it stand for a while. That way the filth settles at the bottom. If you do the same, you’ll be fine.” I did not make this up! I read this advice in the works of an 18th century writer, Louis-Sébastien Mercier, author of Le Tableau de Paris and Le Nouveau Paris. The rich, of course, would have spring water brought from the suburbs. They also drank excellent wines, much the same as our best modern French wines. The poor people drank wine as well, or rather a liquid that went by that name, but had nothing to do with fermented grape juice.