Dr Chris Howick
Papers # 2016 Berlin
Rigid PVC (PVC-U) is a well-established material for pipe systems for drinking water, with use dating back to the 1930s. In order for PVC-U to be used in drinking water systems, manufacturers must comply with all of the relevant regulations. These include self-assessment systems, where manufacturers demonstrate that only approved raw materials have been used in the pipe's manufacture (and forbidden substances are not used), testing of the finished pipe in accordance with recognised quality standards and may also include detailed assessment of both the pipe composition and performance by recognised test institutes which act on behalf of government agencies.
The regulatory system for drinking water pipe is underpinned by the European Drinking Water Directive (EU directive 98/83/EEC) which gives thresholds for certain undesirable substances for drinking water. In addition to that companies must seek national approvals according to the member state in which the pipe is to be installed. The precise details of this differ from country to country. Since the mid-1990s there have been attempts to bring about either full or partial harmonisation of drinking water approvals in the EU through the so-called four member state process. This will be reviewed.
Of key importance, wherever installation is to be made, is that PVC-U provides a polar polymer with both amorphous and crystalline regions that act so to give the material high strength and, importantly, excellent resistance to the migration and extraction of any ingredient that is used as a polymer additive, polymer production aid or lubricant. Analysis of migration from PVC-U formulations showing migration below detection limits will be presented - work which was performed to ensure that migration from PVC-U could be successfully modelled using up to date migration modelling systems. The combination of long standing use, approvals in member states no matter which system of approval is in use, and the low migration nature of the polymer matrix shows why PVC-U has been, remains, and will be a key part of pipe formulations for drinking water applications.