Can I Use Stainless Steel to Brass in Well Plumbing?

If you’re upgrading or repairing a private well system, you may be asking: “Can I use stainless steel to brass connecting well plumbing?” It’s a smart question—mixing metals in plumbing isn’t inherently wrong, but it can cause serious problems if done incorrectly. In this guide, we’ll break down the science, safety, and best practices so you can make informed, long-lasting choices for your well system.

Is It Safe to Connect Stainless Steel to Brass in Well Plumbing?

Short answer: Yes—but only with proper precautions.

Stainless steel and brass are both commonly used in well systems. Stainless steel offers exceptional corrosion resistance, especially in harsh groundwater conditions, while brass provides good machinability and pressure tolerance. However, when these two dissimilar metals come into direct contact in the presence of an electrolyte (like well water), galvanic corrosion can occur.

🔍 What is galvanic corrosion?
It’s an electrochemical process where one metal corrodes faster when in electrical contact with a different metal, especially in conductive environments (e.g., water with dissolved salts or minerals).

According to the Galvanic Series of Metals (a standard reference in corrosion engineering), stainless steel (passive) is more “noble” than brass, meaning brass will act as the anode and corrode preferentially when the two are connected in water.

📌 Key Insight: In aggressive well water (high in chlorides, sulfates, or low pH), this corrosion can accelerate—potentially leading to leaks, reduced pipe life, or contamination.

When Is Stainless Steel-to-Brass Connection Acceptable?

Not all situations are equal. Here’s when it’s generally safe to connect stainless steel to brass in well plumbing:

✅ Short-term or low-risk applications (e.g., above-ground fittings in dry environments)
✅ With a dielectric union or isolation fitting (more below)
✅ In neutral-pH, low-mineral well water (test your water first!)
✅ When using 316L stainless steel (more corrosion-resistant than 304)

According to the Plumbing-Heating-Cooling Contractors Association (PHCC), dissimilar metal connections are permissible if galvanic corrosion is mitigated through proper design.

💡 Pro Tip: Always test your well water’s chemistry first. High conductivity (>500 µS/cm) or low pH (<6.5) increases corrosion risk.

How to Safely Connect Stainless Steel to Brass: Step-by-Step

Follow these steps to minimize risk and ensure code compliance:

Step 1: Test Your Well Water

Use a certified lab or at-home kit to check:

• pH (ideal: 6.5–8.5)
• Total dissolved solids (TDS)
• Chloride and sulfate levels

⚠️ If TDS > 500 ppm or pH < 6.0, avoid direct metal-to-metal contact.

Step 2: Use a Dielectric Union

A dielectric union contains a non-conductive plastic or rubber barrier that electrically isolates the two metals.

Installation Checklist:

1. Shut off the well pump and drain the line.
2. Cut pipe cleanly with a tubing cutter (no burrs).
3. Install the dielectric union with stainless side on one end, brass on the other.
4. Tighten to manufacturer specs (typically 25–35 ft-lbs torque).
5. Pressure-test at 1.5x operating pressure for 15 minutes.

📏 Note: Dielectric unions are required by the International Plumbing Code (IPC) Section 605.1 for dissimilar metal connections in potable water systems.

Step 3: Avoid Threaded Direct Connections

Never screw stainless steel directly into brass (or vice versa). Threads increase surface contact and trap moisture—accelerating corrosion.

Instead, use:

• Flanged connections with dielectric gaskets
• Compression fittings with polymer sleeves
• PEX transition adapters (if compatible with system pressure)

Stainless Steel vs. Brass in Well Systems: Pros & Cons

🌐 Did You Know? Lead-free brass (often labeled “DZR” – Dezincification Resistant) is now required for potable well systems under the U.S. Safe Drinking Water Act. Learn more about brass alloys on Wikipedia.

Real-World Case: What Happened in Ohio?

In 2021, a homeowner in rural Ohio connected a stainless steel submersible pump directly to a brass pressure tank fitting—without a dielectric union. Within 18 months, the brass fitting corroded, causing a slow leak that contaminated the well with sediment.

After water testing revealed high sulfate levels (720 ppm), a licensed plumber replaced the connection with a 316 stainless-to-brass dielectric union and installed a pH neutralizer. No further issues occurred over the next 3 years.

🛠️ Lesson: Even “minor” connections deserve corrosion planning—especially in private wells where water chemistry is unpredictable.

FAQ: Stainless Steel & Brass in Well Plumbing

Q1: Can stainless steel and brass touch in dry plumbing?

A: Yes. Galvanic corrosion requires an electrolyte (like water). In dry, indoor applications (e.g., decorative fixtures), direct contact is generally safe.

Q2: What’s the best stainless steel grade for well plumbing?

A: 316L (low carbon) is ideal. It contains molybdenum, which boosts resistance to chlorides—common in groundwater. Avoid 304 in high-chloride wells.

Q3: Do I need a dielectric union for every connection?

A: Only where dissimilar metals contact and are exposed to water or moisture. If using PEX or PVC as a buffer, a dielectric union may not be needed.

Q4: Will galvanic corrosion happen immediately?

A: Not always. It can take months or years—depending on water chemistry, temperature, and surface area ratio. But once it starts, it accelerates.

Q5: Can I use Teflon tape on stainless-to-brass threads?

A: Teflon tape does not prevent galvanic corrosion. It seals leaks but doesn’t stop electrical contact. Use a dielectric union instead.

Q6: Are there plastic alternatives to avoid metal mixing?

A: Yes! Schedule 80 PVC or CPVC can transition between metals. Just ensure pressure/temperature ratings match your well pump specs (typically 100+ PSI, 140°F max).

Conclusion: Yes, You Can—But Do It Right

So, can you use stainless steel to brass connecting well plumbing? Yes—you absolutely can, as long as you prevent galvanic corrosion through smart design. Always:

• Test your well water first,
• Use a dielectric union or non-conductive barrier,
• Choose corrosion-resistant grades (316L stainless, DZR brass),
• Follow local plumbing codes.

A few extra minutes of planning today can save you thousands in repairs—and protect your water quality for years.

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