Slab Plumbing Leak? PEX to the Rescue!

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Do you have a plumbing leak in a supply line under your slab foundation? Tearing up your flooring and digging a trench in the middle of your house is one answer. However, running a bypass of PEX through your attic may be the simpler, quicker and cheaper answer.

Let me explain with a personal experience of a burst rolled copper supply line:

Years ago I was headed out the door and heard the sound of water going through the pipe out of the water heater. I had places to go and people to see, so it registered, but I didn’t think too much about it at that moment.

When I returned home, the water heater was running. I could still hear a little trickle of water too.

Being that it was hot water, which only gets turned on by something running in the house, my mind immediately raced to, “Who could be here in the house?” and then “Who left a faucet running?”

At the time, I lived alone so the first idea was terrifying and beyond creepy! However, the likelihood of someone breaking in and taking a leisurely shower with only a trickle of water was probably very low. While checking all the bathrooms, kitchen and laundry, I remembered the cat was sitting at an odd location on the other side of the wall from the water heater. So I checked out the cat’s new very odd location. It was warm!

Much to my horror (and relief from the above concern) I ended up with a water pipe leak under the slab of my home right by the water heater. After immediately turning off the old-school gate valve shutoffs thus preventing more water from going through the water heater, there were two big questions to address:

#1 What is the layout of the hot water plumbing in the house?

Did all the water get distributed out in the wall next to the water heater? Was there one line that went out and there is a diverter type thing that distributes the water to different lines (which I found out the technical term was manifold) hidden in some other wall of the house? Or was it even worse–were supply lines split off under the slab?

A couple phone calls later and a plumbing locator service was scheduled for the next day. He mapped out the layout of the plumbing in both the floor and the walls. It was much nicer option than making holes in drywall…

The forensic plumber detected there was a mini manifold in the wall next to the water heater. One run to the kitchen, one to the powder room and laundry and another to the two full bathrooms on the other side of the house. Of course, he confirmed the location of the under slab plumbing leak. Unfortunately, the leak was in the long distance run from the water heater to the bathrooms.

#2 How should the new line be run?

The thought of ripping out rooms of tile just to rerun this line of hot water to the bathrooms was sickening. While the idea of updating the tile in my place was somewhat attractive, the tile really wasn’t that unattractive and it is nicely done. Even more important–it is *DONE*. It was the one surface I haven’t touched other than the granite slab countertops in the kitchen.

The attic was a simple and easy choice.

At the time, we were not superstar plumbers. Sweating copper was not in our tool chest yet. If this is you too at this moment, don’t sweat it. 😉 PEX is the easy and inexpensive answer!

We ran a continuous line from the hot water manifold to the manifold dividing the water between the master bathroom and the shared full bathroom. Once we pulled the line across the house we hired a plumber to sweat the old copper manifolds to a Sharkbite PEX-C crimp connector on either end of the PEX.

SharkBite connections are generally known to be temporary fixes in the plumbing world. In this case, though, going from copper to PEX isn’t just an easy connection. The solution for the bypass was not push-to-fit, it was crimp to a new soldered connector! I left the walls open for a year. Honestly, if it wasn’t for hosting my own wedding rehearsal dinner at the house, it might still be open. In any case, the original intent for leaving the walls open for some time was to make sure the connections did not leak. In addition, I wanted to make sure the temperature swings through the hot months as well as the cold months did not cause a leak. The connections held with absolutely zero drips.

My dad and I repaired the drywall the week before the dinner, when I was still perfecting my hairstyle for the big event.

For those of you further north than Phoenix, you might be thinking, what happens when it freezes in the winter? We chose SharkBite PEX-c because it was the only PEX readily available to us in a coil from the Home Depot locally. Although PEX-c is not one of the most flexible and forgiving types of PEX (we go with PEX-a now), it’s been freeze and thaw tested in multiple tests–the PEX stretches and contracts as the states of water change. We also wrapped it in pipe foam insulation for extra insurance.

For further proof, Matt Risinger made a video on the performance of PEX in a freeze / thaw enviroment.

One unexpected bonus of bypassing a leak with PEX through the attic: instant heat!

…in the summer. You are no longer waiting as the cooler water waiting in the line below the house goes down the drain. In the summer months, you have your very own instant heat without a recirculating loop!

The PEX line gets nice and toasty in the attic, even encased in a sleeve. Even though I’m sure the attic is well into the 120’s or hotter in the summer here in Arizona, the water isn’t scalding. It cools off by the time it goes back down through the wall to the old manifold, then back up to the shower head. You still have a little gap of cool water between the attic run and the hot water heater, but it isn’t terrible.

In the winter you are back to waiting for the entire line. Gotta have some silver lining with the summer months where we hibernate in air conditioning here!

An unfortunate, expected con.

As is clearly evident in my drawing above, the downside is we have now introduced an additional sixteen feet of supply line going up and down the walls to the manifolds, which are located close to the ground. Sixteen feet of ¾” hot water line. It’s a lot of wasted water for every single time you want hot water in either bathroom. It’s still better than ripping up the tile…or no hot water, but it still hurts.

If you are here more than a week after this post goes live, I’m going to venture Google sent you here because you are searching for what to do with your very own under slab plumbing leak. This isn’t your best home ownership day ever. I feel your pain!

This is one of those events that happened well before the blog started. The lack of pictures is an indication of where I was at the time–too busy to take a picture of the manifolds popping up from the slab in the walls. I hope there IS NOT an opportunity to take a picture again!!!

I almost accepted my boyfriend’s marriage proposal while he was shoving the PEX in the attic down through the wall to the water heater. In retrospect, it  would have been one of the best proposal stories *ever*. Missed opportunity on my part.