Is the tap water in France safe to drink?

In 2017 the "linternaute" did some tests on water quality in some big French cities. They wrote an article (in French) about it.

They also tested the water quality in Toulouse which seemed to be very good.

Personally I would drink water from the tap throughout France, never got sick and I have been on vacation there every year in different places.

A rough translation of the text on the page:

L'unique réseau alimentant cette commune du Sud-Ouest en eau le fait avec moins de 5% d'analyses non-conformes suivant les dernières analyses des Agences régionales de santé, en terme de "limites de qualité" (les critères pour lesquels des normes non-respectées peuvent représenter un danger pour la santé). Un argument de plus pour inciter les Toulousains à consommer l'eau du robinet, un geste bien plus écologique que l'eau en bouteille, effet de serre oblige : l'eau minérale en bouteille parcourt 300 kilomètre par an en moyenne dans les camions-bennes. Le prix de l'eau du robinet à Toulouse est le troisième moins cher au m³ parmi les villes de plus de 100 000 habitants à la qualité de l'eau du robinet "bonne pour 100% des réseaux" en France.

The single network feeding this southwest commune with water does so with fewer than 5% of non-conforming analyses, according to the latest analyses of the regional health authorities, in terms of "limits of quality" (the criteria for which broken standards can represent a health danger.) Another argument for Toulousains to consume tap water, a much more ecological action than bottled water, is the greenhouse effect: bottled mineral water travels 300 km per year on average in trucks. The price of tap water in Toulouse is the third cheapest per cubic meter among the cities with more than 100,000 inhabitants for which all networks in the area had "good" quality of tap water.

Yeah, I do it every time I visit and have never had an issue. I see all the locals doing the same thing, the restaurants serve us tap water and the schools have drinking fountains from the same thing.

You can get a rough estimation of how safe tap water in a country is by looking at the WHO map detailing the use of safely managed drinking-water sources. Roughly, tap water is OK in countries with >75% of population using safe water sources. This threshold will indeed depend on how certain you choose to be, and the location you stay at. E.g. in decent hotels, tap water will usually be fine even in countries which are just above 50%, because such hotels will have above-average water quality. If you're staying in a sleazy motel on a countryside, it wouldn't be unreasonable to refrain from drinking fresh tap water in countries where less than 90% of water sources are safe.

For my level of risk aversion, filling up a bottle from an hotel sink in Toulouse would be fine.

I agree that the tap water is safe in the most of countries.

But I have a personal rule: do not drink tap water in any place when I am traveling.

Why? It could be safe for local residents, but the water could have microorganisms that your body never saw before.

I already had issue during trips for different countries and lost part of my vacation staying sick. So, usually I buy a big bottle of water and use my small bottle in my backpack