The Right Plumbing System for Healthier Water

Ongoing conversations surrounding the use of certain materials in plumbing systems, and the effects they may have on consumers’ drinking water, have put metallic fittings under the spotlight. As this scrutiny has grown, so too has the need to find new, innovative piping solutions. With that in mind, Franz Huelle, head of technical at  REHAU Building Solutions explores the viability of alternatives in today’s plumbing systems

From the first terracotta pipes in around 1700BC to modern day technology, the art and science of plumbing has changed over the years. Many materials have been used in the heating and plumbing space, with lead being perhaps the most infamous. Though very stable and malleable, the health risks incurred through the metal’s high toxicity levels resulted in it being banned from use in pipework over 30 years ago.

Since then, the industry has evolved – brass fittings and pipes enjoyed increasing popularity among building specifiers and service providing, becoming the material of choice for over 70 years. In recent years, however, certain materials have come under increasing scrutiny for the effect they can have on drinking water once installed.

Because these materials can leach undesirable substances such as lead into water drunk by consumers, they may pose a health risk.

An open letter

Indeed, an open letter sent earlier this year from the UK’s Water Regulators to water companies raised these concerns. The letter, which addressed the suitability of metallic materials in contact with drinking water, cited findings from UK Water Industry Research (UKWIR) identifying that metallic fittings can be a major source of elevated metal ion concentrations in drinking water. Notable in UKWIR’s research was the link drawn between some brass fittings and the levels of lead and nickel in drinking water.

Currently, the effect of non-metallic materials in drinking water is assessed via the stringent criteria set down in British Standard (BS) 6920 and WRAS has been for many years administering an approval scheme including this test to determine the level of metals leaching from non-metallic fittings that are in contact with water. Though testing and approval processes do exist to assess the potential for metallic materials to adversely affect potable water, the British Standards Institute’s 2002 ‘Draft for Development Standard’ has been shown to be unsuitable as it is unrepresentative of real use.

Investigations have also shown that when compared to their non-metallic counterparts, no corresponding system exists to effectively determine long-term leaching characteristics from metallic fittings, or carry out reliable testing.

Recent scientific research has highlighted that metal leaching rates can increase in the first few months following the installation of new metallic fittings. In response to this, the 4MS Group – an initiative between the UK, France, the Netherlands and Germany to harmonise drinking water requirements – codified performance criteria to provide guidance around the use of metallic fittings in contact with water.

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Even less risk

These criteria are collated in BS EN 15664, which sets standards around assessing the potential for metallic materials to adversely affect drinking water quality. Metals that have been successfully tested to BS EN 15664 are added to the ‘Common Composition List,’ available via the 4MS Website. Alloys found in this list can be used to manufacture metallic plumbing fittings to reduce the risk of metals leaching into the water.

However, it must be pointed out that, unless the fitting is completely free of lead, there always remains a small risk of lead leaching into the water. It should also be noted that under current regulations, 4MS Group’s criteria is optional. So, while the risk to consumers may be reduced and compliance improved in some products, not all metallic fittings have been tested to a level where they can provide a guaranteed level of protection.

Fitting solutions

Faced with such a scenario, it may be more prudent for specifiers, building designers and other building service providers to opt for plumbing pipe systems that use a high proportion of non-metallic components and fittings made from alloys found in the ‘Common Composition List’, such as REHAU’s RAUTITAN plumbing system, which uses lead-free gunmetal.

Although debate continues over the use of plastic fittings over metallic alloy options, issues arising from metal leaching and drinking water should set such polymer-based systems apart as a more logical option.

Advances in polymer-based plumbing solutions means that plastic alternatives to brass are able to offer a safer, stronger, more flexible and, crucially, more hygienic system for builders and developers.

RAUTITAN, for example, delivers on durability, corrosion resistance and ease of installation.

Its cavity-free impermeable joints eliminate the risk of microbial contamination, and its smooth surface prevents deposits from forming. Because of this, both the RAUTITAN flex and its multi-layer sibling RAUTITAN stabil enjoy WRAS approval.

Because polymer plumbing systems such as these do not use lead, the designer can also ensure that water quality within the building is improved. Under the right conditions, brass fittings are subject to the risk of stress corrosion cracking. Because this is not an issue with polymer alternatives, it removes the possibility of lead leaks and the contamination that could ensue.

Through reducing the amount of metals used in plumbing systems wherever possible and only relying on metals tested against BS EN 15664, designers can enjoy peace of mind, knowing issues surrounding the presence of undesirable substances in drinking water have been avoided.

By contrast, due to the lack of adequate, mandatory testing and assessments systems available for metallic fittings, stakeholders opting for this solution run the risk of long-term leaching into drinking water supplies. Not only could this affect a designer and builder’s reputation later down the line, it could also impact the health of the building’s occupants.