Branchements d'eau potable à Paris. Expérimentation de matériaux de substitution au plomb

Drinking water branch of Paris

Compagnie des Eaux de Paris, 5-7, avenue Percier 75008 Paris

Résumé

En décembre 1992, les médias ont amplement fait état des problèmes liés à l'utilisation du plomb pour acheminer l'eau potable.

Suite à l'émoi suscité, la ville de Paris a décidé d'agréer comme matériau le polyéthylène haute densité pour la réalisation des branchements neufs d'eau potable de 20, 30 et 40 mm de diamètre.

Ce document présente les premiers résultats des recherches, entreprises dès 1991, expérimentant d'autres matériaux de substitution au plomb compatibles au contexte particulier des égouts parisiens.

Le choix des matériaux s'est porté essentiellement sur des tuyaux en acier inoxydable rigide ou souple. Ces derniers sont composés selon les fournisseurs de parois interne et externe tout inox ou d'une paroi externe inox et interne caoutchouc.

Les matériaux tout inox n'ont pas révélé d'altération de la qualité de l'eau après six mois de service, en revanche la vigilance s'impose à l'égard des branchements à paroi interne en caoutchouc qui feront l'objet d'essais et d'analyses complémentaires.

Abstract

Since 1985, water distribution in Paris has been entrusted to "la Compagnie des Eaux de Paris" (subsidiary of CGE) in the 14 districts on the right bank and to "la Société Parisienne des Eaux" (SLE subsidiary) in the 6 districts of the Seine left bank.

The water is supplied to the gates of the city by SAGEP (Société Anonyme de Gestion des Eaux de Paris) and quality is checked by CRECEP (Centre de Recherche et de Contrôle des Eaux de Paris).

In December 1992, the media gave a great deal of coverage to problems linked with the use of lead as a means of conveying potable water.

In response to the resultant upheaval, the city of Paris decided to approve high density polyethylene as a material for making new 20, 30 and 40 mm diameter potable water connections.

This document gives the initial results of the research begun in 1991 as an experiment with other substitution materials for led, compatible with the specific contexts of the Paris drains.

The choice of materials concerned more essentially rigid or flexible stainless steel pipes.

- Rigid stainless steel connections are made up of straight or curved stainless steel tube sections assembled by STRAUB-GRP stainless steel unions.

- Flexible stainless steel connections are made up of two inner and outer walls, all stainless steel, or an outer stainless steel wall and an inner rubber wall, depending on the suppliers.

The survey went hand in hand with a check of mechanical and technical knowledge conceming high density polyethylene:

- construction of connections with heat-welded unions (development of a specific technology for drains with the creation of a generator offering full safety features).

- follow-up of non-permeation of the surrounding environment into the water being conveyed.

The implementing of these materials took place in June 1992.

The very first flexible stainless steel pipe installations immediately proved that they were particularly advantageous because of the flexibility and lightness of the material.

Six months after their installation, four flexible stainless steel connections were removed to analyze any phenomena of deposit and corrosion and to examine the effects upon the quality of the water and on any degradation of the materials.

All stainless materials showed no change in the water standards.

Conversely, pipes with rubber inner walls disclosed to the naked eye the presence of bacteria colonies, subsequently confirmed by bacteriological analysis.

To conclude,

Vigilance is necessary regarding connections with an inner wall of rubber which will be the subject of complementary tests and analyses.

All stainless structures require some technical perspective regarding ageing that might occur and an in-depth economic balance.