Renewal of the drinking water network in the energy canal – Tenon Hospital, Paris

The Challenge

Tenon Hospital in Paris operates an extensive drinking water network, most of which dates back to the 1950s and 1960s and is installed in walk-in energy canal. The corrosive environment led over decades to progressive corrosion, leakages, and restricted functionality of valves.

The challenge was to renew the existing cast-iron network while the hospital remained fully operational – in an environment with limited accessibility, strict hygiene requirements, and without interrupting the drinking water supply. 
What was required was a reliable, durable, and corrosion-free piping solution specifically suited for installation in energy sewers. The lightweight properties of polyethylene made it easy to move in this confined installation area. 

The Solution

Together with the executing contractor SADE, the client decided on a fully fused piping system made of HDPE from Aliaxis. The solution is specifically designed for corrosive environments and enables a homogeneous, permanently leak-tight piping system. This ensures a permanently safe drinking water quality while sustainably reducing maintenance requirements and life-cycle costs.

Aliaxis supported the project from technical consulting through to on-site assistance, including training and the provision of tools. 

The Realisation

The implementation was carried out in close cooperation among all project stakeholders. As part of the measures, the existing drinking water network was completely converted from cast iron to a polyethylene piping system. The renewal was carried out directly in the hospital’s walk-in energy canal, under difficult installation conditions and during ongoing operation. 
The newly installed network reliably supplies the hospital with approximately 100,000 m³ of drinking water per year. By a homogeneous, fully fused HDPE piping system, a permanent, corrosion-free solution with high operational reliability was achieved. 

The Aliaxis products used – including FRIALEN electrofusion fittings and FRIALOC shut-off valves – were specifically selected for use in energy canal. Implementation was completed on schedule and to a high standard of workmanship. 
Since commissioning in February 2025, the drinking water network has met all requirements for hygiene, security of supply, and sustainability, while enabling the operator to significantly reduce maintenance efforts. 

The Conclusion

This reference project demonstrates how aging drinking water networks can be renewed efficiently, safely, and economically – even under challenging conditions. With FRIALEN Safety Technology from Aliaxis, the project owner received a future-proof, low-maintenance solution that offers long-term investment security and fully meets the requirements of critical infrastructure.

For municipal utilities, public suppliers, and network operators, the project confirms: HDPE system solutions from Aliaxis enable the sustainable modernization of existing networks while ensuring high operational reliability and low life-cycle costs.