When choosing the right metal and finish for plumbing fixtures, hardware, or architectural fittings, it’s not just about how they look—it’s also about how the metals and water interact. Brass and stainless steel are the two most common materials for visible fixtures. Both resist rust better than plain carbon steel, but they behave very differently in use.
This is a short, practical guide for durability, common ways fixtures fail, finishes, and best practices for avoiding problems, along with a helpful graph and trusted sources.
At a Glance: Brass vs Stainless Steel
- Brass (primarily copper + zinc): Brass demonstrates high machinability, such materials are attractive and possess antimicrobial properties and are often used for making valves and tap fittings. However, there are brass alloys which can become weak in harsh water environments because of dezincification or stress corrosion cracking. Canada
- Stainless steel (iron + ≥10.5% chromium + nickel + molybdenum): This group consists of stainless steel materials. These have the ability to resist corrosion due to the chromium oxide layer present within the iron-based composition of stainless steel. Various types of stainless steel exist. Some of the most common and widely used types would be ‘304’, ‘316’, of which ‘316’ requires the addition of molybdenum to resist corrosion. In aggressive environments, pitting corrosion may occur in stainless steel.terrauniversal.com
Failure Modes and What They Look Like
- Dezincification (brass): When certain types of water (stagnant, highly acidic or alkaline, or with high chloride or sulfate content) come into contact with the alloy, zinc dissolves out. The result is a porous, copper-rich skeleton, which is very weak and brittle. The appearance can be described as reddish, porous, crumbly, and less flow because of the obstruction within the pipes. This can be alleviated by the use of dzi (dezincification-resistant) copper alloys, proper water chemistry management, and the application of linings and protective coats. Canada
- Pitting and crevice corrosion (stainless): Roughness involves the presence of small pits and under-deposit corrosion that may cause perforation on the walls when the majority appears intact. This has been observed and initiated by chlorides and oxygen depletion or damage on the passive layer. Prevention involves the use of highly alloyed material (for instance, 316, 904 L, and 254 SMO in severe environments) and proper passivation processes in order to maintain the passive layer and eliminate crevices where salts tend to collect. Nickel Institute
- General corrosion and tarnish: Brass can tarnish through surface oxidation and may develop green or black patinas over time. Stainless steel, by contrast, does not typically corrode uniformly, but it can still undergo color changes in certain conditions, such as heat tinting or contamination on the surface.
Finishes and Their Role In Durability
- Electroplated chrome or nickel on brass: If the plating is intact and free of porosity, it gives the surface a great look and protects it from corrosion. Plating hides the risk of dezincification underneath. A plated brass part can hide internal damage until it breaks. It is important to check things regularly and keep an eye on the quality of the plating.
- PVD / Physical Vapor Deposition coatings on stainless: PVD on stainless steel is tough but can be scratched. It has thin, hard coatings that don’t seal like plating does and keep their color over time.
- Mechanical finishes (polish, brushed): Surface finishes affect how dirt and deposits accumulate. Brushed finishes hide scratches but can trap debris that contributes to localized corrosion. Highly polished finishes shed dirt more easily and are simpler to keep clean.
- Passivation (stainless): a chemical process (using nitric or citric acid) that gets rid of free iron and makes a strong oxide film. ASTM A967 sets out the rules for passivation and tests to see if they work. This is a common requirement in the industry for stainless steel parts used in corrosive or sanitary settings. In corrosion tests, properly passivated stainless steel parts work better than unpassivated parts. ASTM International
Design and selection guidelines (practical)
- Match alloy to environment. DZR (dezincification-resistant) brass and 316 stainless steel are both solid choices for indoor plumbing systems that use treated drinking water. In chemical or high-chloride environments—such as areas exposed to saltwater, marine conditions, or industrial cleaning agents—opt for stainless steel with corrosion resistance equal to or greater than 316, or consider duplex and super-austenitic grades for even higher protection. plumbing-components.com
- Prefer DZR brass for potable water When you need brass for its machinability or cost advantages, choose a manufacturer that is properly certified and follows local regulations limiting lead content and requiring resistance to dezincification. plumbing-components.com
- Use passivation post-fabrication For stainless steel components, specify proper passivation and require treatments that comply with ASTM A967 and AMS 2700 when the parts will be used in demanding environments. ASTM International
- Avoid hidden failure traps. Plated brass can look perfect on the outside while losing zinc on the inside. For critical pressure-containing parts, use solid corrosion-resistant alloys, or ensure the plating remains intact and that inspection intervals are appropriate.
- Consider coatings and linings (internal fluoropolymer or epoxy linings) For brass components exposed to corrosive fluids, apply internal linings to prevent the metal from coming into direct contact with the environment. These linings significantly reduce the risk of dezincification, but they must be applied carefully and correctly to be effective.
Cost Vs Lifetime Trade-Off
Brass is usually cheaper and easier to work with, while stainless steel is more expensive but often lasts longer and requires less maintenance in harsh chemical environments. When modeling lifecycle cost, you should factor in the cost of replacement or repair, downtime, and the risk of major failures (such as leaks in building services).
Quick checklist
- Require passivation certificates for stainless (ASTM A967 / AMS 2700). ASTM International
- Specify alloy grade (e.g., EN CW602N / DZR brass, 316/316L stainless), not just “brass” or “stainless”. plumbing-components.com
- Require plating/finish thickness and porosity tests if plating is used.
- For potable water, confirm compliance with local lead-free / drinking-water standards and dezincification resistance tests. Canada