Pipe fittings and the new Drinking Water Directive

You could be forgiven for thinking that, since lead pipes have not been permitted for use with drinking water supplies for decades, the problem of lead in drinking water has gone away. Not so. New legislation coming into force in December this year focuses attention on the issue, and the responsibility for ensuring that lead content is within defined limits lies with the installer.

The issue relates to the European Drinking Water Directive (DWD 98/83/EG). This sets the standard for the microbiological and chemical water quality of drinking water. One of the particular issues for consideration is the permitted level of lead. When the Directive originally came into effect in the UK in 2003 the permitted lead level was 25μg/litre. However, this limit was always seen as interim and it was planned that the limit would be reduced to 10μg/litre at the end of December 2013. The requirement for this new, lower level to be achieved is now therefore just around the corner.

The legislation is also very clear that it is the responsibility of the installer working with the drinking water pipework to make sure this exacting standard is met. The installer therefore needs to be aware of how lead can get into the water and how to avoid this happening.

Traditional solution
Lead used to be a common material for pipework both for mains and smaller residential pipes. However, in the 1970s lead was identified as an element that can have an adverse effect on mental development of infants and children. The result was that lead pipework was prohibited and has not been in use for new installations for decades. However, many pipes still remain in older properties – often as the service pipe connecting the water main to the house – especially if the kitchen has not been modernised.

The problem with lead pipework is that lead can leach from the pipework into the water supply. The issue is lessened in hard water areas because of the scale that forms on the inside of the pipes and helps protect against the dissolution of lead. In soft water areas water companies generally treat the water with orthophosphate to reduce the problem. However, even when this is done particles of lead may build up in older pipes and intermittently appear in tap water.

Another cause of lead in tap water is the illegal use of lead-based solder to join together sections of copper pipe. This type of solder is only sold for use on closed-circuit central heating systems, but incorrect use or DIY work on drinking water pipes can lead to this material coming in contact with drinking water. In some areas (although this is rare in the UK) lead may also be present in the ground water that forms the basis of the water supply.

What this means for the installer is that the drinking water in the distribution system cannot be guaranteed to be absolutely free of lead: it is therefore critical that the work being carried out introduces no new sources of potential lead contamination.

This focuses close attention on the materials being used, in particular, the brass and other alloys used in the manufacture of fittings. Lead is often added to brass and other alloys in concentrations of around 2% to improve the malleability and therefore machinability of the material. Since lead has a lower melting point than the other constituents of these alloys, it tends to migrate towards the surface where it can more easily leach into the water supply, while cutting and shaping of the material may also inadvertently lead to the dispersal of the lead content.
The quantity of lead concerned is relatively low and it therefore only becomes a problem with the new legislation. The issue creates a technical challenge for manufacturers who need to design relatively complex fittings without using lead in the metal.

Material gains
At Sanha we decided to meet the problem head-on by developing a patented 100% lead free alloy material from which we can now manufacture a range of lead free components to help installers comply with their obligations. It took the company five years to develop the lead free material and the manufacturing process for its range of press and threaded fittings. This range now includes the Series 3000 threaded red brass fittings; the Sanha-Press Series 8000 and the Series 25000 3-fit-press fittings for use with copper and composite pipes.

Use of such materials allows the installer complete assurance that if lead is detected in a system it has to have originated from the water source or elsewhere upstream of the works, ensuring that the installer is not liable for any remedial work required to eliminate the problem completed.

Find out more
The Sanha lead-free fittings are packaged in a distinctive green packaging with a ‘Pb-free’ logo on the label.