Which lead-free brass works for NSF 61 and NSF 372 machined water parts?

What does “lead free” mean under the Safe Drinking Water Act?

Under Section 1417 of the Safe Drinking Water Act, a pipe, fitting or fixture is “lead free” when the weighted average lead content of its wetted surfaces is not more than 0.25 percent, and solder or flux is lead free at not more than 0.2 percent (Public Law 111-380). “Lead free” is therefore a legal threshold, not a claim of zero lead.

The threshold was set by the Reduction of Lead in Drinking Water Act, signed on January 4, 2011, which rewrote the definition in Section 1417 and took effect 36 months after enactment, in January 2014 (Public Law 111-380, section 2(b)). Before that change the limit for pipes and fittings was 8 percent lead, according to the EPA summary of the rule, which is why the leaded free-cutting brasses were acceptable in plumbing for decades and are not today.

The EPA turned the statute into a regulation in 2020, 40 CFR part 143, subpart B. It repeats the definition and calculation almost verbatim, prohibits both installing and selling a non-compliant product, and adds a certification duty, covered further down, that the 2011 law did not have.

The rule also lists what it does not cover. Products used only for nonpotable services, such as industrial processing, irrigation and outdoor watering, are exempt, and so are products plainly marketed for conveying something other than water, including air, hydraulic fluids, refrigerants and gases. Toilets, urinals, fill valves, shower valves, tub fillers, fire hydrants, service saddles and water main gate valves 2 inches in diameter or larger are exempt by name (40 CFR 143.16). A brass part for a natural-gas meter set is therefore outside the rule, even though it may look identical to a water part; your own drawing or customer specification still governs the alloy.

Which lead-free brass alloys replace C36000 in machined water parts?

For bar-fed turned parts the usual choices are C69300, a silicon brass, and C27450, a low-lead yellow brass; for cast bodies that are machined afterward, C87850 is the cast counterpart of the silicon brass. C36000 free-cutting brass cannot meet the limit when it makes up most or all of the wetted surface, and even a small wetted share of it uses up most of the 0.25 percent budget.

The table compares the four grades using the Copper Development Association’s alloy records, which list the ASTM product specifications each alloy is sold under. Lead is the row to read first, but read it the way the law does: for a range, the maximum counts.

Two things stand out. C27450 has a lead maximum of exactly 0.25 percent in its CDA record, the same figure as the legal limit, so a product made entirely from it meets the weighted average with no margin, and any coating or second wetted material with more lead would push it over. C69300 and C87850 have a lead maximum of 0.09 percent (CDA, C69300), which leaves room for the other components in an assembly.

The silicon brasses are also a different alloy family, not just C36000 with the lead removed. They carry much more copper, their strength is higher and they list faucet stems, water valve bodies and water meter cases among typical uses in the CDA record.

How is the weighted-average lead content calculated for a fitting?

For each wetted component, multiply its lead percentage by its share of the product’s total wetted surface area, then add the results; the maximum of the material’s lead range is always the figure used. Only surfaces that touch water count, so a leaded part that is fully outside the water path does not enter the sum.

The method is written into the statute and repeated in 40 CFR 143.12. The same section adds two rules that affect machined parts. If a coating is applied to an internal wetted surface, the maximum lead content of both the coating and the alloy under it is used. If a permanent liner seals a leaded surface away from the water, the liner’s lead content is used instead.

A worked example shows why margin matters. Take a valve whose body is 80 percent of the wetted area and whose stem is the other 20 percent, in the way the formula in the statute is written. With both in C69300 at a 0.09 percent maximum, the weighted average is 0.09 percent. With both in C27450 at 0.25 percent, it is exactly 0.25 percent, still compliant but with nothing left for a plated or coated surface.

What should you ask a machining supplier for on a lead-free brass part?

Ask for the alloy by UNS number and product standard on every mill test report, with lead reported as a measured value, plus a statement of how lead-free and leaded stock are kept apart. Those documents feed your own wetted-area calculation and your certifier’s file.

A practical request list for the RFQ and the first article:

• The alloy called out on the drawing in full, for example “C69300 per ASTM B371”, and a note that substitution requires written approval.
• A mill test report for each heat or lot, showing the chemistry including lead, traceable to the bar or casting used.
• A description of how bar, remnants and chips of leaded and lead-free alloys are segregated and marked; a mixed bar passes every dimensional check and fails only on chemistry.
• Whether an incoming chemistry check is run on the bar, and by what method.
• The cutting fluid and the cleaning step used before packing, since both can matter for an NSF/ANSI/CAN 61 leach test on the finished product.
• Any plating or coating on wetted surfaces, with its composition, because it enters the lead calculation. The surface finishing page lists the finishes our partner plants apply, and the quote names where each step is done.

Do not accept a supplier’s own “NSF approved material” wording as a substitute for your product’s certification. Saola’s ISO 9001 certification is in progress and not yet held, and Saola does not hold an NSF product listing; the documents above are what a component supplier can provide. The RFQ preparation guide covers the rest of the package, and parts for gas and water service are described on the gas and water distribution page.