Lead-free bronze alloys contain no more than 0.25 percent lead on wetted surfaces, the limit set by the U.S. Reduction of Lead in Drinking Water Act that took effect January 4, 2014 (Public Law 111-380). The main families are bismuth bronze (grades C89320, C89833, and C89835), silicon bronze (C87600, C87850), and aluminum bronze (C95400, C95500, C95900). Bismuth bronze typically holds 1 to 3 percent bismuth, which replaces lead as a machining aid. Before 2014, copper alloys were allowed up to 8 percent lead, so the shift to a 0.25 percent ceiling reshaped how plumbing, valve, and bearing parts are specified (Copper Development Association, 2024).
What is lead-free bronze?
Lead-free bronze is any copper alloy that meets the 0.25 percent maximum lead content on surfaces that contact drinking water, as defined by U.S. federal law. The category exists because traditional leaded bronzes used lead as a machining aid and a solid lubricant, and that lead can leach into water or the environment.
Removing lead is not as simple as deleting an ingredient. Lead made bronze easier to cut, so lead-free grades use substitutes like bismuth or rely on different alloy chemistry to stay machinable. The result is a family of alloys engineered to match the old performance without the health and regulatory risk. Bismuth bronze is the most direct replacement, and we cover it in depth in our guide to bismuth bronze composition and properties.
Why did the lead limit change to 0.25 percent?
The limit changed because of the Reduction of Lead in Drinking Water Act, which took effect on January 4, 2014. It lowered the allowable weighted-average lead content on wetted surfaces of pipes, fittings, and fixtures to 0.25 percent, down from the previous federal ceiling of 8 percent (Public Law 111-380, amending Safe Drinking Water Act Section 1417).
That is a thirty-fold reduction, and it applies to any component that dispenses water for human consumption. Valves, meters, pump parts, faucets, and fittings all fall under it. RoHS (Restriction of Hazardous Substances) adds a parallel limit on lead in electronics. For a product team, the practical effect is simple: if a bronze part touches drinking water or ships into a regulated market, it has to be a certified lead-free grade, and the material choice belongs in the design phase, not after.
Bismuth bronze — the lead-free workhorse
Bismuth bronze is the most common lead-free replacement for leaded red brass and bearing bronze. It uses bismuth, typically 1 to 3 percent, in place of lead to keep the alloy machinable. Common grades include C89320, C89833, and C89835.
The grade-for-grade swaps are what make bismuth bronze practical. C89833 is the lead-free replacement for C83600, the leaded red brass long used in valves and fittings. C89835 replaces C93200 (SAE 660), the standard leaded bearing bronze. Bismuth bronze is corrosion resistant, polishes well, and performs in potable water and marine environments. It is the alloy most shops reach for first when an existing leaded part needs a compliant version with similar properties.
Silicon bronze — strength and corrosion resistance
Silicon bronze is a naturally low-lead family known for higher strength and excellent corrosion resistance. Grades like C87600 and C87850 meet the 0.25 percent lead rule and hold their mechanical properties at elevated temperatures better than bismuth grades, which matters during soldering and brazing (NIBCO technical data, 2023).
Silicon bronze is the choice when a potable-water part needs more strength than red brass, or when the part sees marine exposure and stress at the same time. It machines and welds well, resists dezincification, and is widely used for valve stems, pump components, and fasteners. The trade-off is cost, since silicon bronze usually carries a higher material price than standard bismuth grades.
Aluminum bronze — high load and wear
Aluminum bronze is the high-strength, high-wear member of the lead-free bronze family. Grades C95400, C95500, and C95900 are naturally lead-free and can be heat treated to raise tensile strength further. They handle heavy loads, galling, and harsh service that would deform softer bronzes.
This is the alloy group for bushings, gears, valve seats, and bearings under high load, especially in aerospace, marine, and heavy industrial equipment. Aluminum bronze is harder to machine than bismuth or silicon grades and demands the right tooling and cutting parameters, which is where machining experience pays off. For other high-performance materials, see our guides to steel grades for CNC machining and CNC aluminum grades.
Lead-free bronze grades compared
| Family | Example grades | Replaces | Best for | Machinability |
| Bismuth bronze | C89320, C89833, C89835 | C83600 red brass, C93200 bearing bronze | Potable water valves, fittings, bushings | Good (bismuth aids cutting) |
| Silicon bronze | C87600, C87850 | Leaded brass in plumbing | High-strength water parts, marine, fasteners | Good, strong at heat |
| Aluminum bronze | C95400, C95500, C95900 | Leaded bearing bronzes under high load | Bushings, gears, valve seats, bearings | Moderate (needs correct tooling) |
Grade designations and replacements per the Copper Development Association and supplier data (2024). Lead-free defined as 0.25 percent maximum weighted-average lead on wetted surfaces.
Which lead-free bronze should you choose?
Choose bismuth bronze when you are replacing a leaded red brass or bearing part and want similar properties with easy machining, such as a potable-water valve body. Choose silicon bronze when the part needs more strength or sees marine and high-temperature service. Choose aluminum bronze when the part carries heavy loads or faces severe wear, like a bushing or gear.
The deciding factors are the regulatory requirement, the mechanical load, and the environment. A faucet fitting and a high-load bushing are both bronze, but they call for different lead-free grades. Send us the part requirements and the service conditions, and our engineers will recommend the right grade and confirm it machines cleanly before you commit. Start with an instant quote and a free material review, or browse our full materials range.
Frequently Asked Questions
What is the most common lead-free bronze?
Bismuth bronze is the most common lead-free bronze because it directly replaces the leaded red brass (C83600) and bearing bronze (C93200) used for decades. It uses 1 to 3 percent bismuth in place of lead to stay machinable, and it holds up in potable water and marine service while meeting the 0.25 percent lead limit.
Is silicon bronze lead-free?
Yes. Silicon bronze grades like C87600 and C87850 are naturally low in lead and meet the 0.25 percent wetted-surface limit. Silicon bronze also offers higher strength than red brass and keeps its properties better at the high temperatures reached during soldering and brazing.
What does the 0.25 percent lead rule actually require?
The Reduction of Lead in Drinking Water Act, effective January 4, 2014, requires that the wetted surfaces of pipes, fittings, and fixtures for potable water have a weighted-average lead content of 0.25 percent or less. The previous federal ceiling allowed up to 8 percent, so this was a major tightening.
Can lead-free bronze be machined as easily as leaded bronze?
Almost. Lead made bronze cut faster and act as a chip breaker, so fully lead-free grades can be slightly harder to machine. Bismuth bronze closes most of that gap because bismuth plays a similar role to lead during cutting, while aluminum bronze is the hardest of the group to machine.
Which lead-free bronze is best for bearings and bushings?
Aluminum bronze (C95400, C95500, C95900) is best for high-load bearings and bushings because of its strength and wear resistance, and it can be heat treated for more. For lighter-load bushings that replace a leaded bearing bronze, C89835 bismuth bronze is the common drop-in.
Does RoHS apply to bronze parts?
RoHS restricts lead in electrical and electronic products, so it applies to bronze components used inside those products, such as connectors and contacts. For drinking water parts, the Reduction of Lead in Drinking Water Act is the governing rule. Many parts must meet both depending on their market and use.