EDW continues collaboration with the 4MS to define a common risk-based approach for the evaluation of assembled products

EDW advocates harmonized technical requirements that safeguard water quality and consumer protection, and fully supports the 4MS initiative to define stringent but pragmatic evaluation criteria for assembled products.

Divergent national approaches to assessing the hygienic fitness of products in contact with drinking water still prevail within the Single Market. Some approval schemes require the testing of individual materials or components, others prescribe the testing of assembled products to account for a so called “cocktail effect”. Some schemes conduct microbial growth tests on products, others do not. Some schemes use EN standards, others do not.

The relevant CEN Technical Committee (CEN/TC 164) has developed numerous EN standards for the hygienic assessment of materials in contact with drinking water, however standards and evaluation methods for the hygienic assessment of assembled and minor products is still lagging behind. To address this shortcoming, last year the 4 MS has established a task group focusing on “Minor and Assembled Product Testing”, and EDW’s Products Working Group has been actively participating in this endeavor.

At the moment, the scope of the 4MS working group only covers test methods and does not extend to defining the details of production control and product certification, but once the risk-based test regime is fully clarified the group will possibly take on this task as well.

A common risk based approach

The task group has been working on a common risk-based approach, where assembled products that have higher impact on water quality are subjected to more stringent testing and control than products that have lower impact on water quality. According to this approach conversion factors – which are proxies for the impact of the products on water quality - are used to differentiate between products and prescribe a proportional test regime.

The proposed test regime uses existing horizontal EN standards on specific migration testing, organoleptic testing, microbial growth testing and TOC testing as building blocks but it also envisages chemical formulation assessment and testing for unknown substances, and the possibility of conducting all tests (with the exception of the microbial growth test) on assembled product level. 

The framework for a risk-based test regime has already been defined, and in the coming months the group will work on exemplifying this risk-based approach with concrete products, defining how composition testing should be performed and clarifying how screening for unknown substances could be applied.

EDW members and EDW’s Products Working Group will continue supporting the ongoing work of the 4 MS task group by leveraging their product specific knowledge and by using their cross-sectional overview of national technical rules and requirements across Europe.

Adjustment of conversion factors for the assessment of organic and cementitious materials

Another positive development is that the 4MS will make realistic adjustments to its conversion factors for the assessment of organic and cementitious materials, which included an overestimation of the surface fraction of fittings. The total surface fraction of fittings and ancillaries in water distribution was assumed to be 20%, now this is being reduced to 10%. This value is a more correct reflection of reality and results in lower conversion factors and therefore a lower impact category for fittings and ancillaries. Furthermore, to further strengthen a risk-based approach and avoid unnecessary over-testing and over-evaluation of small surface area products a new conversion factor category will be created for small components of fittings which represent less than 1% of the total surface area.