Dr Steve Tuckwell, Managing Director at WRAS gives a warning on using leaded solders...

The plumbers’ merchant told a customer that because lead-free solder was out of stock, he should use leaded solder as nobody ever gets fined for using it.  Read on – and if anyone says this to you, you can tell them why it matters to use the right solder.

‘Not getting fined’ is missing the point. Using lead solder on drinking water systems is illegal but it’s also dangerous to health. You could cause someone to get lead poisoning from their drinking water. It HAS happened.

Lead poisoning from use of solder

A young boy and his father who had been unwell for months without any clear cause, went to see their doctor, who diagnosed lead poisoning. Detective work showed it was from water containing lead. Dad drank a lot of water at home and took hot and cold drinks to work with him. His son regularly took a glass of water at night from a little-used tap in a bathroom.

The lead came from lead-based solder used on the pipework in their recently built home. Despite leaded solder being outlawed for hot and cold domestic water systems since the 1980s, 15% of local houses up to three years old were found to have it. This was not limited to one estate or one plumbing firm.

Ban on use of lead solder

Leaded solder is ONLY permitted where the water can’t be for used drinking, for example on central heating closed circuits.  All other parts of domestic plumbing systems serving kitchen, bathroom and wash basin taps, showers and storage cisterns must be lead-free if soldered. By law, installers have to do this or risk a fine under the Water Fittings Regulations or Scottish Water Byelaws. Where leaded solder is found in drinking water systems, the Water Supplier may require all the joints to be remade at the installer’s cost, including ‘making good’ in an occupied home. Think of the cost!

Alternatives to lead solder

Push-fit and press-fit fittings are alternatives, but for soldered joints, lead free solders are available inintegral solder ring fittings or for end-feed use. Number 23 tin/copper alloy soft solder, made to EN 29453, will ensure that lead levels are not a problem. It is suitable for all soldering work and because it is less dense than lead solder, there’s more joints per 500g reel! 

How does lead from solder get into drinking water?

Solder can run inside the pipe while the joint is being heated. Then, in use, water in the pipe slowly dissolves lead from the solder. The longer the water sits in the pipe between draw-offs, the greater the amount of lead which dissolves. Soft water is known to be aggressive, but hard water can dissolve lead too.  However, in most hard waters, the water hardness eventually deposits a coating over the solder and reduces the amount which dissolves.

Check out the WRAS website for more info - www.wras.co.uk