Plastic pipe compliance for drinking water contact is verified by comparing migration levels of substances contained in the plastics with specific limits in drinking water. In practice, the analytical determination of the migration levels is often a time and costs intensive task. This is especially true for materials like PVC-U, where the migration levels are, in most case, far below the detection limits of the most modern analytical methods.
For such cases, the German Environmental Agency (UBA) and other regulatory authorities recommend the use of modelling for estimating the migration levels. To perform such calculations, a series of input parameters are needed, such as the diffusion and partition coefficients of the migrating substances. This peer reviewed article describes a new approach to estimate conservative but realistic diffusion coefficients for any organic substance diffusing in PVC-U, and the use of these coefficients to predict the migration levels of these substances into drinking water.