Metallic fittings in plumbing are under growing scrutiny as the effects that certain materials may have on consumers’ drinking water continue to be investigated. More than ever, rising concern about the safety of drinking water in homes across the nation drives demand for pioneering piping solutions. With that in mind, Franz Huelle, Head of Technical at REHAU Building Solutions explores suitable alternatives on the market today.

Developments in plumbing technology span hundreds of years, with many materials used in plumbing and heating during that time. Of these materials, lead is possibly the most notorious. The health risks from metal’s high toxicity outweighed its reliability and adaptability, leading to its ban from use in pipework over 30 years ago.

During that time, building specifiers and service providers have increasingly gravitated towards brass fittings, the go-to option for over 70 years. However, recently discussion continues over the use of certain materials and their possible effect on drinking water after installation. Harmful substances such as lead leaching into water supplies could endanger consumers, making piping material choices more important than ever.

Regulator concern

The UK’s Water Regulators recently emphasised concerns to water companies nationwide in an open letter referring to findings from UK Water Industry Research (UKWIR). It highlighted the correlation between some brass fittings and lead and nickel levels in drinking water as part of wider investigation into how metallic fittings can be a major source of elevated metal ion concentrations in water.

Rigorous criteria codified in British Standard (BS) 6920 has governed the assessment of the effect of non-metallic fittings in contact with drinking water. For years, WRAS has been putting an approval scheme into practice, resulting in reliable, standardised assessment of metal leaching levels from non-metallic components. Though testing and approval processes assessing metallic materials’ contamination of drinking water systems exist, the British Standards Institute’s 2002 ‘Draft for Development Standard’ is unrepresentative of real use and therefore unsuitable.

According to other investigations, in comparison to their non-metallic counterparts, metallic fittings have no equivalent means of determining their long-term leaching effects in place, nor a system to implement consistent testing.

Increases in leaching rates in the months after installation of new metallic fittings have been noted in recent scientific research. The 4MS Group – an initiative between the UK, France, the Netherlands and Germany harmonising drinking water requirements – responded to this by establishing guidelines and performance criteria around metallic fittings in drinking water systems.

Protection not guaranteed

Presented in BS EN 15664, these criteria set practices and precedents for evaluating potential drinking water contamination by metallic materials. Tested metals that adhere to BS EN 15664 join the ‘Common Composition List,’ available via the 4MS website. Alloys on this list are therefore suitable for use in plumbing fittings, with reduced risks around leaching into drinking water systems.

However, it is also notable that unless the fitting is totally lead-free, the metal could still potentially leach into the water. Furthermore, 4MS Group’s guidelines are not mandatory. Therefore, although risk to consumers is potentially lower and compliance among metallic fittings improved, the testing does not guarantee protection.

Fitting solutions

Stakeholders may find it more practical to select pipe systems with more non-metallic components as well as fittings made from alloys presented in the ‘Common Composition List’, such as REHAU’s RAUTITAN, a lead-free gunmetal system. While discussion over plastic fittings instead of metallic alloy options continues, problems surfacing from metal leaching into drinking water ought to highlight the need for responsibly selecting the right metal alloy.

The development of such systems has afforded contractors a safer, stronger, more flexible and more hygienic alternative. For example, RAUTITAN provides durability, corrosion resistance and ease of installation. Its smooth surface prevents deposits forming and its cavity-free impermeable joints eliminate microbial contamination risk. Consequently, both RAUTITAN flex and RAUTITAN stabil enjoy WRAS approval.

As polymer systems such as these are lead-free, designers can guarantee improved water quality within their buildings. By contrast, brass fittings can experience stress corrosion cracking. The possibility of lead leaching and the  impact on health can therefore be eliminated through polymer alternatives.

Reducing metallic component used in plumbing systems and using only BS EN 15664 approved metals reassures designers that problems arising from drinking water contamination have been avoided. Because of an absence of suitable, mandatory testing for metallic fittings, those choosing other metals may compromise water supplies through long-term metallic leaching. As well as jeopardising contractor reputation going forward, this could also affect consumer wellbeing.

For more information about REHAU’s RAUTITAN, visit


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