Mike Dolt Enterprises
Mike Dolt Enterprises
User: Little Bill, Location: Tennessee NEC:2017
Asked on: Thursday, January 23, 2025 at 2:21 pm EST
Answered on: Thursday, March 6, 2025 at 7:43 am EST
Question: If you have copper piping to a water heater, can you use a stainless steel supply line, or would you need a copper supply line. I'm talking about flexible supply lines with female ends.I'm removing a section of the copper and adding the supply line. The end of the supply line to the existing copper line would thread on a copper coupler.
Yes, you can use a stainless steel flexible supply line connected to copper piping and a copper coupler. This is a common and generally accepted practice.Here's why: Dissimilar Metals and Galvanic Corrosion
The primary concern with connecting dissimilar metals in plumbing is galvanic corrosion. This occurs when two different metals are in contact in the presence of an electrolyte (like water), and one metal corrodes preferentially. However, in this case, the potential for galvanic corrosion is low due to several factors:
Stainless steel is more noble than copper
Stainless steel is more corrosion-resistant than copper. When these two metals are coupled in water, the copper becomes the anode and will tend to corrode more than the stainless steel. However, type 304 or type 316 stainless steel are resistant to corrosion and are commonly used with copper.
Small Surface Area
The surface area of the stainless steel relative to the copper is small. This means that even if some minor galvanic corrosion occurred, it would be a localized effect on the copper.
Water Quality
The water quality plays a role. If you have highly acidic or alkaline water, the risk of corrosion is higher.
Dielectric Unions (Usually Not Necessary)
While dielectric unions are often recommended when connecting dissimilar metals, they are typically unnecessary in this situation because of the factors above.
Code Compliance
This setup generally meets plumbing code requirements in most jurisdictions. However, it's always a good idea to check your local codes for any specific regulations.
Therefore, using a stainless steel flexible supply line with a copper coupler to connect to existing copper piping is a standard and acceptable practice.Important Considerations
Use Quality Materials
Ensure you use high-quality stainless steel flexible lines and copper fittings that meet industry standards.
Inspect Regularly
Periodically inspect the connection points for any signs of corrosion or leaks.*
Consider Water Quality
If you have known water quality issues, you may want to consult with a plumber.
In summary, you're fine to use the stainless steel supply line in the configuration you described. Flag for review