With plumbing system materials under scrutiny due to growing concerns around metallic components contaminating drinking water, building services professionals are searching for new, innovative alternatives to maintain drinking water quality. Franz Huelle, Head of Technical at REHAU Building Solutions, discusses the issues and alternatives available in the current market.

Plumbing systems and materials are constantly evolving, from the first terracotta systems to modern-day PE-Xa pipework. Perhaps the most infamous material was lead, which, which was banned from use in pipework over 40 years ago following healthcare concerns.

Plumbing material choices have since changed, with specifiers and building service providers often favouring brass and copper. Yet, their use is now being scrutinised due to potential health risks from these materials leaching into water supplies via metallic components.


Addressing the issue

A 2019 open letter from the UK’s Water Regulators raised concerns over metallic leaching into drinking water supplies, referring to findings from UK Water Industry Research (UKWIR), which established links between metallic fittings in contact with drinking water and elevated concentrations of metal ions in drinking water supplies. Also prominent in UKWIR’s research was the increased nickel and lead levels within supplies potentially leaching from brass fittings.

The current reference point for assessing the impact of non-metallic materials used in pipework is represented by criteria in British Standard (BS) 6920. The Water Regulator’s Advice Service’s (WRAS) approval scheme also includes evaluation of levels of metal leaching from non-metallic fittings in contact with drinking water supplies.

Though testing determining potentially adverse effects metallic components have on water supplies exists in the British Standards Institute’s 2002 ‘Draft for Development Standard,’ WRAS declared this unsuitable and unrepresentative of real use. Investigations have also highlighted that, unlike non-metallic testing, no corresponding system or reliable testing determining long-term leaching effects of metallic fittings are in place.

Recent scientific research dictates that, in the months following installation, metal leaching rates from new metallic fittings can rise. In response, the 4MS Group – an initiative between the UK, France, the Netherlands and Germany to harmonise drinking water requirements – organised performance criteria guiding the correct use of metallic plumbing fittings coming into contact with water.


Avoiding risk

Informing this new criteria, BS EN 15664 sets precedents for assessing potentially harmful contamination of drinking water from metallic materials. Metals adhering to BS EN 15664 can be used for plumbing fittings to reduce metal leaching into water and are added to the ‘Common Composition List’, available via the 4MS website.

Nevertheless, unless fittings are completely lead-free, small risks of lead leaching into will remain. It is also worth acknowledging, under current regulations, the 4MS Group’s criteria are optional. Therefore, despite improved products’ compliance reducing consumer risk, guaranteed levels of protection cannot be assured as not all available metallic fittings have been assessed correctly.

For the first time in preparation for being added, the candidate list for Annex XIV under the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) regulations now includes lead. Otherwise known as the REACH Authorisation List, Annex XIV lists chemical substances deemed a Substance of Very High Concern that should no longer be available on the market or used after given dates without authorisation.

With pressure on manufacturers and plumbing solutions providers to ensure they use compliant materials for fittings and focus on using lead-free, non-metallic leaching materials in pipework, the need for alternatives is growing.


Polymer protection

Such investigations and codes of practice mean specifiers, designers and other professionals may find non-metallic components more attractive when selecting plumbing solutions, using fittings with materials found in the ‘Common Composition List’.

Though discussions about prioritising plastic over metal fittings in plumbing systems continues, risk of metal leaching into drinking water should render polymer-based systems the more practical alternative. Given advances in polymer solutions, plastic alternatives are now an even safer, stronger, more flexible and more hygienic choice for contractors.

Systems like REHAU’s RAUTITAN heating and plumbing solution comply with standards, particularly with the introduction of its REACH-compliant, lead-free gunmetal RX+ fitting. A durable and easy-to-install system for safe drinking water solutions, RAUTITAN’s cavity-free impermeable joints eliminate risk of microbial contamination and smooth surface prevent deposits forming. Thanks to this and the new RX+ fitting, both RAUTITAN flex and the multilayer RAUTITAN stabil enjoy WRAS approval.

Reducing metallic component quantities and adhering to BS EN 15664, Annex XIV of REACH, and the ‘Common Composition Lists’ will ensure specifiers and designers can maintain excellent water quality. If stakeholders instead opt for using inadequately tested metallic fittings, they could risk contamination from long-term leaching. Alongside the negative impact on health, this could also damage contractors’ reputation going forward.

For more information about RAUTITAN, REHAU’s universal 10 bar pipework solution for drinking water and heating systems, visit

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