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Image: Cut away of a faucet showing solder on brass pipes.

Brass is a copper alloy that contains:

  • zinc (5-40%) as the principal alloying element,
  • tin,
  • iron,
  • aluminum,
  • nickel,
  • silicon, and
  • lead.

Zinc is added to brass to increase tensile strength. Tensile strength is the greatest stress a substance can bear without tearing apart. Lead is added to improve “machinability.” Materials with good machinability require little power to cut, can be cut quickly, easily obtain a good finish, and do not wear the tooling as much. Lead also makes castings pressure tight by filling the voids created as the casting cools. In the past, brass, used to make household fixtures, contained 1.5-7.5% lead.

Solder is a metallic compound used to seal plumbing joints. In the past, most solders contained about 50% lead.

Issue

Distribution Systems and Household Plumbing

Homes that have lead solder, or homes that are connected to the water main by a lead service line, are more likely to have higher levels of lead in their water. Experts regard this lead-containing solder as one of the major causes of lead contamination of household drinking water in U.S. homes.

Corrosion Characteristics and Concerns

Brass fixtures and solder act as sources of dissolution corrosion. Dissolution refers to the dissolving of the metals (that make up the alloy) into the liquid in contact with the metal. In this way, metals such as lead, copper, chromium, and cadmium can dissolve from brass fittings into our drinking water.

Brass fixtures (including faucets) act as sources for dezincification corrosion. Dezincification is the leaching of zinc from the alloy, leaving behind a porous, copper-rich structure that has little mechanical strength. This weakens water pipes and result in blockages.

Action

The 1986 amendments to the Safe Drinking Water Act banned the use of solders containing more than 0.2 percent lead in public water systems and household plumbing. The use of lead in pipes and brass fixtures was restricted to 8 percent or less under the Safe Drinking Water Act Amendments of 1996. Despite this regulation, lead-containing solder may still exist in older water systems and homes.

Results and Impact

Technical Contacts

Darren Lytle
513-569-7432

Michael Schock
513-569-7412

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