Can a slab leak be repaired with epoxy in the copper water pipe?

The answer is Yes and No.

The question should be, what is epoxy lining?

Epoxy lining, commonly misrepresented as Epoxy Restoration, is merely a water safe glue that coats the inside of copper water pipes. It is typically about as thick as house paint.

Leaking Water Pipes Can Be Repaired Using Epoxy!

Just like you can plug a leak in an automobile tire using that liquid rubber compound in a can. This process involves opening up the manifolds in the walls on each side of a dedicated line that is leaking. The line is then blown dry with a compressor and a two part epoxy is poured into the line and pressurized. This may need to be done a couple of times depending upon the size of the leak. It takes about a day to perform. Success rates vary, but the line is plugged the majority of the time. The problem with this repair process is that it is not a listed repair according to the Uniform Plumbing Code and I have yet to see any of the manufacturers of the epoxy state that this is an approved repair either.

Leaking Water Pipes Can Not Be Properly Repaired Using Epoxy!

If you listen to those infomercials on the television you could think that a can spray rubber and epoxy that looks like play dough can fix anything. This is type of repair you will be achieving when using epoxy to plug holes rather than to help prevent interior corrosion. This is the solution that the Department of Defense was after when they experimented in the 1970s and later published a report in the 1990s about the effective use of epoxy lining. I have been unable to find any published reports stating the accuracy and efficacy or epoxy actually plugging holes. The main thrust of the Epoxy Process was to isolate galvanized steel water piping from the corrosive nature of water. They wanted to prevent rust and this has morphed into a copper relining system. Epoxy Restoration isn't a copper water pipe restoration anymore than painting your car is a vehicle restoration system.

It is a Band-Aid at Most

Epoxy lining is a fairly new way to help prevent copper water pipe lining under concrete and behind walls without a lot of destruction to the home. The coating, if done properly, adds a layer of protection the copper water piping helping to prevent corrosion from the water. Unfortunately, most water lines under concrete burst and develop pin holes from outside sources that the epoxy lining does not address.

Epoxy Lining Will Not Solve These Water Pipe Leak Problems:

• Dents in the copper piping from improper installation
• Water Corrosion from a circulating line that is moving too fast
• Sediment buildup from a circulating line that is moving too slow
• Electrical Short Circuit corroding the copper piping
• Vibrations wearing outside the outside of the piping
• Earth Movement shearing the piping

Epoxy Warranties Sure Seem to be Disingenuous

I have pulled the following from a very popular Epoxy Coating website: “Epoxy pipe lining has a design life of 40-60 years. Since epoxy lining prevents the number one cause of pipe failure – corrosion – epoxy lined pipes can be expected to outlast metal plumbing systems.” Notice the word “design life” and “metal plumbing”. “Design life” is meaningless, but gives the impression of an epoxy coated pipe life span of 40-60 years. “Metal” does not directly refer to “copper” and since a epoxy coated galvanized steel pipe will outlast an unprotected one this is a true statement. What is not being said here is that copper water pipes already come with an up to 50 year warranty.

But In Any Case

It is not the epoxy that will fail. It is the pipe and the existing pipe is not under the epoxy manufacturer’s warranty. Even the warranty on the copper piping seems to somewhat bogus. I have never seen copper pipe fail because of the pipe. It is because of the installation and the application, the hardness of the water and other non-pipe related defects. The State of California has a maximum home warranty for new construction (latent defects) of 10 years. After this time, with very limited reasons, a homeowner cannot sue the manufacturer or the plumbing contractor for defective work. This means that your warranty is a maximum of 10 years.

(The picture is really the summation of the entire water pipe restoration process for slab leak repair. The only way to inspect the piping is to cut it open and take a look. If you are not doing this you are at the mercy of the plumber who performed the epoxy lining process. Upper left - not enough epoxy in the pipe, middle picture - too much epoxy in the pipe slumping and stopping water flow, lower right - ragged ridges cause turbulence and this can wear the piping out and in this picture it appears that the epoxy was torn off the interior walls of the piping by the turbulence.)

If You Want to Protect Your Home From Future Slab Leaks

I really don’t see the harm in epoxy coating the interior of your home piping other than the process itself is not inspectable so you will not know whether or not the job was done properly. It is water safe, it is durable and it may indeed help to prevent some slab leaks in the future. There is only one way to prevent slab leaks from happening the future and that is to bypass all of the copper water piping located under the slab of your home.