Brass fittings and dezincification
Entry in Metal pipe · Updated · Written by the Know Your Pipes editors from the sources listed under References
Dezincification is corrosion of brass in which zinc is removed from the alloy, and it matters because brass, an alloy made mainly of copper and zinc, is used throughout household plumbing for valves, faucets and fittings[1][4]. Brass is golden in color, and brass pipe and fittings are usually joined by threads[1].
1 Brass and lead
Until recently, most brasses contained between 2% and 8% lead[2]. EPA notes that brass faucets, fittings and valves made before 2014 are likely to contain lead, and Penn State Extension notes that brass fixtures can leach lead even in homes with plastic water lines[1][5].
Federal law now limits pipe, fittings and fixtures sold as "lead free" to 0.25% lead, calculated as a weighted average over the surfaces that touch water[3]. Non-leaded brasses typically carry lead only as an incidental impurity, around 0.1% to 0.25% by weight, and use bismuth, or bismuth with selenium, in place of lead[2]. The NSF/ANSI 372 entry explains how that limit is certified.
| Item | Older brass | Current "lead free" brass |
|---|---|---|
| Lead content | Typically 2% to 8%[2] | Weighted average no more than 0.25%[3] |
| Lead substitute | None | Bismuth or bismuth with selenium[2] |
| Lead risk | Likely in parts made before 2014[1] | Low, incidental impurity[2] |
2 Dezincification
Health Canada lists dezincification of brass among the sources of lead-bearing particles in tap water, alongside solder particles and pipe deposits[2]. Water chemistry affects how fast it happens: high-alkalinity, low-chloride water is associated with less dezincification, and zinc orthophosphate treatment by a water utility can slow the rate[4].
Because zinc loss and lead release both depend on the water, the same brass part can behave differently from one supply to another. The utility's water quality report and a lab test are the practical guides for a given house.
Related entries: Kitec pipe, a plastic system with brass fittings; dielectric unions; compression fittings; and shutoff valves.
See also
- Lead pipe and lead service linesSoft gray lead water pipe, mostly in service lines; how to recognize it and what EPA's 2024 rule requires of water systems.
- NSF/ANSI 14 (plastics piping)The NSF standard for plastic pipe, fittings and related materials, and what its pw, dwv and other end-use marks mean.
- Kitec pipeMultilayer plastic-aluminum water pipe with brass fittings made by IPEX; its fittings were prone to dezincification and leaks.
- NSF/ANSI/CAN 372 (lead content)The standard used to certify plumbing products to the federal 0.25% lead-free limit, and how to read its marks.
- Compression fittingsThreaded fittings that seal when a nut squeezes a brass or plastic sleeve onto the tube; common at supply stops and on small tubing.
- Dielectric unionsThe insulated union that joins copper to galvanized or other steel pipe to slow galvanic corrosion, and why it can still fail.
References
- U.S. Environmental Protection Agency, "Know Your Plumbing: Remediate lead in drinking water in child care facilities" (2025) — epa.gov
- Health Canada, "Guidelines for Canadian Drinking Water Quality: Guideline Technical Document – Lead" — canada.ca
- U.S. Environmental Protection Agency, "Use of Lead Free Pipes, Fittings, Fixtures, Solder and Flux for Drinking Water" — epa.gov
- Health Canada, "Guidance on Controlling Corrosion in Drinking Water Distribution Systems" — canada.ca
- Penn State Extension, "Lead in Drinking Water" — extension.psu.edu