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Components produced by metalcasting are an integral part of water distribution, both in the delivery systems as well as in-residence plumbing components. Traditionally, the copper-based alloys used in water works castings included lead as an alloying element. However, new regulations have been implemented that limit the amount of lead in materials used for potable water (water for human consumption) and many lead-free casting alloys have been developed and put into service to meet these new standards. Many in the water industry continue to search for that “single best no-lead alloy” to fit all needs. However, it is unlikely that any single alloy will be able to make the wide variety of casting sizes and geometries needed for water distribution. Plumbing components currently in use in the marketplace are being cast in several different copper no-lead alloys. This alloy variety demonstrates that multiple metallurgical choices are available that meet current government regulations and can be tailored to provide the best performance for each specific component application.

The current regulations require all products contacting potable water must be lead-free (as defined by the law). The metalcasting industry began the conversion to lead-free alloys in the 1990s in anticipation of the new regulations. The conversion accelerated from 2006-2013 as the new rules began taking effect. The first laws started in California and Vermont (as of 1/1/2010), followed by similar regulations in Maryland (2012) and Louisiana (2013). The laws became effective nationally with the passage of U.S. Public Law 111-380 (effective 1/4/2014). The federal directive mandates the use of 0.25% maximum lead content for products used in the installation or repair of water systems and plumbing providing water for human consumption. The lead percentage is determined by a weighted average lead content formula (based on the original California law), and supersedes the previous EPA Safe Drinking Water Act, Section 1417. The rules exempt material used for water not anticipated for human consumption, such as non-potable services, service saddles, distribution main gate valves, and fire hydrants. However, many of those components have been converted to no-lead casting alloys as well.

Copper alloy castings are part of water distribution for industry and homeowners in four primary areas: hydrants, the water delivery system (the water main to the in-house meter), water meters, and in-home plumbing components (water meter to the faucet). More than 30 copper alloys are listed in the ASTM standards as containing a maximum of 0.1% lead, and several more are listed that contain a maximum of 0.25% lead, the limit set in the new regulations. In addition, research is ongoing and new alloys continue to be developed and enter the marketplace. The following is a review of common alloys, current applications and relevant industry specifications. The alloys are listed using the industry standard Unified Numbering System (UNS).

Fire Hydrants—Historically, hydrants have been cast in a several different ASTM bronzes and brasses. Although exempted from the new regulations, hydrants are currently made in a variety of lead-free ASTM bronzes, brasses, and stainless steel. Hydrants are manufactured to meet American Water Works Association (AWWA) Fire Hydrant Standards.

Waterworks Products (water main to the residence)—Previously cast in leaded brass alloy C83600, commonly known as 85-5-5-5 (containing 4.0-6.0 % lead), these components have been converted and are now cast in lead-free copper alloys. The primary alloys used are C89520 (bismuth selenium), C89833 (bismuth-brass) and C89836 (bismuth-bronze). Components are manufactured to AWWA Standard C800 for underground service.

Water Meters—Traditionally produced in lead containing alloys C83600 and C84400, meters are now manufactured in a number of lead-free cast and forged copper alloys, as well as stainless steel, and plastic/composite materials to adhere to AWWA Water Meter Standards.

Plumbing Products (in-home devices, faucets etc.)—Formerly produced as copper alloy castings, brass forgings, die castings and bar stock, most are now made in a variety of lead-free cast copper alloys, stainless steel, and plastic/composite materials to meet various plumbing codes, standards, and certifications.

While metalcasters have many no-lead alloy choices that meet current government regulations, some alloys are more suitable for certain types of applications. Each alloy has properties that make it unique and provide specific benefits. And, each alloy also has melting and casting production challenges. Materials are generally selected to provide the optimum component performance at the lowest cost to the consumer. Relevant specifications and standards provide guidance for material selection. Some of the factors to consider when selecting an alloy include:
•    Castability, including fluidity to fill the mold cavity, pouring temperatures, melting concerns (gas pick up, etc.).
•    Mechanical properties reflecting casting integrity and microstructure.
•    Chemical composition.
•    Pressure tightness.
•    Machinability and related issues.
•    Soldering and brazing capability.
•    Recycling—both in house recycling and external scrap stream.
•    Component specifications and requirements. What performance standard does the component need to meet?
•    Corrosion protection.
•    Alloy cost and availability. Who makes it and how much is available? How available is the alloy in the scrap stream? How abundant are the alloying elements?

Among the number of no-lead casting alloys available today, the most common alloys being used for water components are bismuth brass and bronze, silicon brass and bronze, and low lead sulfur tin bronze. The following provides some guidelines for using these alloys.  

Alloy Selection
While no single alloy will work best for every application, the wide variety of alternatives for lead-free copper alloys provides the opportunity to select the best possible lead-free alloy for each specific component.

The selection lies within the prerogative of the component manufacturers to decide which alloy will assure the production of the highest quality products at the best possible price. Although component application and relevant specifications will be the major driving factors when selecting a no-lead alloy, manufacturers and designers also will consider the total cost of the final component.

The alloy material cost is a part of the equation, but the total overall component cost also includes the impact of the full manufacturing, finishing and recycling processes. Current market availability and long-term sustainability of the alloy are also factors to consider.