Underground Leak Repair: Fixing a Water Leak Below a Concrete Slab

A water leak under your concrete slab can be one of the major problems you run into as a homeowner. It's a lot more common occurrence than you might think. Whether you have the skills to tackle the problem of fixing the leak yourself or not, this video will give you a good understanding of what your options may be and hopefully allow you to save some money in the process of getting water flowing in your home again.

[@rolandopizana7598]

Mr.Rusty the problem is to save money The Contractor told The Plumber to run The Copper Pipes under the slab instead of running them in the attic. P.S. My Dad was A Master Plumber and this was one of his Pet pevees!! He used to say it's better to replace sheetrock in the ceiling and walls then break concrete!!

[@RustyDobbs]

Your Dad was right, Rolando! It probably was a money saving idea to run copper under the slab when that started. I built my house on a pier and beam type construction primarily to let me be running water lines while it was being framed. I have sure been glad over the 30 years since I built it to have the flexibility to access all my plumbing as needed. I have a large crawlspace and even poured some concrete sidewalks and lighted it. Your Dad and I would get along well, I bet!

[@torigay1057]

Amazing, clear, and informative video. Thank you! Every owner of a home with a concrete slab should see this!

[@RustyDobbs]

Thank you for watching, Tori, and for your kind comments! I'm glad you found it helpful!

[@MrCakers]

Incredible Blender work as always Rusty! Glad to see you around.

[@RustyDobbs]

Thanks for watching, John, and thanks for the comment!

[@thereal_johnle]

Rusty this is the first video I've seen like this and it's so amazing the amount of time and effort you put into making this video

[@RustyDobbs]

Thanks for watching and for your comments! Yeah, I enjoy the 3D world and the video did take a lot of time to make but the good thing is that I could produce the same thing in about a quarter of the time now and it would be better quality. That's the benefit of working through projects like this. Thanks again for your kind comments and I'm glad you enjoyed it!

[@OneLeggedTarantula]

When I got a slab leak, I opted to immediately re-plumb the house using pex, routing a loop in the attic with wall drops. Fairly easy and my hot water loop allowed me to setup a circulation pump on my tankless and have instant hot water!

[@RustyDobbs]

Sounds like a good solution for you. Yeah, understanding the idea of what needs to be done to pull off a repipe is not difficult. Getting access to all the areas you need to get to do it becomes the bigger task but what a relief when it is done! No more worries about another leak under the slab!

[@anthonykaiser974]

The hot water recirculation alone would make it worth it.

[@taquitovargas]

This video is awesome thank you for taking the time on making it. It sure helps to see another way to fix a leak. Im definitely going to try it.

[@RustyDobbs]

Thanks for watching and for your comment, Taquito! Yes, sometimes it's a good thing to think creatively when dealing with water leaks in copper piping particularly. You can never be sure if the leak in copper is a fluke one off event, or are there other locations that are close to springing a leak as well. Good to think through all the options before you start spending money digging up your concrete slab!

[@dannywilsher4165]

Awesome video, Rusty!!!

[@RustyDobbs]

Thanks, Danny! Finally got it up!

[@FreeAmerican-mm2my]

I have never seen a video like this. Thank you

[@RustyDobbs]

Hey, thanks for watching! I appreciate it! Yes, I enjoy using the animation software. It can help with explanations.

[@SyberPrepper]

Incredible video and so much great information. I had a similar situation in my house and bypassed with PEX. Animation and video is fantastic. Great job on it all!

[@RustyDobbs]

Thanks for watching, Syber, and for your comments. Yeah, it's a relatively easy thing to do with Pex conceptually. The process can be more challenging at times, but what a simple solution to a big problem with great tools available these days!

[@conchim99]

I have hot spot on the floor in my bathroom. Can I bypass with PEX if I can isolated the leak? Thanks

[@SyberPrepper]

@@conchim99 There's a good chance you can bypass but it depends on your house design and whether the hot water line is accessible.

[@conchim99]

@SyberPrepper I think it is leaking from down stream after the bathtub because my water heater is located outside in side yard near the city water meter. I can break open the back of the facet and reroute from there a long the wall. There is a second bathroom that has exposed hot water copper pipe running vertical inside the closet that houses the central air heater unit. It was hot to the touch. I could use that and hug pex line along the wall go in the back of the facet.

[@SyberPrepper]

@@conchim99 Just remember, you'll have to make a copper to PEX junction (I forget what it is called, I'm not a plumber.) somewhere which will need to be soldered. The PEX connects to the other end. Hopefully in a place that easy to get at and not near anything flammable. Make sure you shut off valve shuts the water off completely. If not, you'll have a hard time soldering the pipe if any water remains in the pipe. Also PEX doesn't bend around corners very well so you may need some 90 degree fittings. Best of luck.

[@BooneLovesVideo]

Wow, incredibly cool visuals here Rusty!

[@RustyDobbs]

Hey, thanks, Boone!

[@adilenecastillo2136]

OMG.. that first animation is incredible! And I haven’t finished the video but I had to say it!

[@RustyDobbs]

Thanks for watching, Addie! Yeah, lots of fun (and hours) to figure a lot of this out. You may remember that it is Blender that I am using. With the way you can handle Sketchup, you could start picking up Blender in a hurry!

[@adilenecastillo2136]

Ok. I finished now. Lots of hours for sure..!! I really can’t wrap my head around all the work you had to do, not only to figured everything out and fix it, but also to put all those animations together afterwards! I feel like crying of physical and mental exhaustion imagining the process! I have tried a couple times to use Blender, but still it is very challenging for me. I can’t seem to find the beginning of it, so because of this, I deeply value this video and all the effort and time you pour into your projects 🎉🎉

[@RustyDobbs]

@@adilenecastillo2136 Hey Addie. Yeah, Blender is not easy and can seem a lot overwhelming. The KZbin tutorials I would recommend are by Grant Abbitt and he has a playlist called Blender 3 Complete Beginners Guide. I have not been through it but it is pretty current and I really like his teaching style. If you go to the CG Boost Academy website, they have a free beginner's tutorial that I have gone through parts of and it is good. It may be a little dated with new versions of Blender but the basic tools are the same. I have bought a number of their courses over time too but that is not necessary to get started. You just need to get some basic skills down and have a little success to get you hooked. As a creative tool, it is much better than Sketchup.

[@adilenecastillo2136]

Thank you so much for the recommendations. My Summer vacations start this Thursday so it is perfect for a switch of routine. This will be in preparation of a -far- future kitchen remodeling. By the way, any explanation of water leaks coming out from the basement’s cracks only when it rains?

[@RustyDobbs]

@@adilenecastillo2136 Probably the simplest explanation is the best. Water collects where gravity sends it. In this case, after rain against the exterior wall of your basement where there just happen to be some cracks that let it come through the wall. Solution: stop the water from flowing there by diverting it during rain (french drains or gutters) or sealing the outside of your basement walls with waterproof sealant (probably not easily accessible).

[@wks7696]

Amazing video! Thank you for sharing. Curious about how you would fix an exit leak from drain to sewage.

[@RustyDobbs]

No sure I completely understand your question, but drains and sewage lines are not pressurized so the answer is pretty straightforward. Anything that will stop the flow of water is a solution. If it’s a crack or a loose connection of parts that screw together, there are products on the market to try to seal those areas. Thanks for watching!

[@dasanagadde]

"A picture is worth a thousand words" ... awesome job with the graphic demonstrations Rusty ..... teaches a lot. Thank you !!!

[@RustyDobbs]

Thanks so much for your comments, dasanagadde! Yes, this was my first 'deep dive' into creating some pretty serious graphics in a program called Blender about a topic that homeowners should have a basic understanding of. Glad you found my approach informative and I appreciate you letting me know!

[@MrJohnweez]

Whoa. You have gotten even fancier in animation and design layouts. Really cool to see the progression

[@RustyDobbs]

Yes Sir, MrJohn! When learning Blender, you can learn a little and never be able to do anything useful. Or, you can work harder at it and begin to see the potential. I'm tapping about 1% of Blender's capabilities but learning fast! Thanks for watching and for your comment!

[@jaymzx0]

I live in a 30 year-old two bedroom bottom floor condo with hot and cold water in the slab. There have been a growing number of units around the property experiencing leaks and needing to jackhammer out the floor to repair it. One poor lady was living with family for six months during the repair simply because they couldn't find the leak. Her floor was Swiss cheese by then. When they found it, they repaired it, only for another leak to show up as soon as they pressurized it. I'm making a mental note of this. If I'm unfortunate enough to have the experience, I may just have everything, hot and cold, redone in PEX in the walls. Drywall is probably a LOT cheaper, and as you pointed out, it's only a matter of time before it happens again! I may be a cynic, but something tells me that insurance would argue for some reason.

[@RustyDobbs]

Thanks for the story, Jay! I’m afraid it is a pretty common occurrence, much more than people think. The reality is there are solutions like running Pex through walls and ceilings that that can solve the problem that sometimes can be very simple depending on access. It is hard to trust copper lines under a slab that have already sprung a leak before!

[@tonvand.4601]

Great video. Did you use 1/2 inch PEX? Did you get the same flow as before?

[@RustyDobbs]

Yes, 1/2" Pex for this repair as it feeds the kitchen sink and washing machine. The first repair we did about 15 years ago we ran 3/4" copper to get more volume to the back bathrooms. In either situation, the water flow has not been an issue. Interesting sidenote... this past week the water heater in the video started leaking so we had to make a quick mid-week swap of it. Video to follow! Thanks for watching!

[@weenfain2321]

They don’t make men like this anymore. Men now call men like this. As a woman whose husband is absolutely amazing but always worked behind a desk and myself repair small Motors and simple repairs just buying our first home after 23 years and knowing immediately it was slab leak, found out fast im absolutely not qualified also calling a guy to take care of it lol and y’all deserve every penny for your work.

[@RustyDobbs]

Yikes! Sorry you all ran into a water water leak under your slab with your first home purchase! Unfortunately it happens pretty frequently. Just this past week, the water heater in this video started leaking after nine years, so we did a quick replacement of it! Video to follow. The joys of home ownership! Thanks for watching and for your comments!

[@StarrTile]

Reading the comments I am learning something new, this blender thing I'll investigate, looks very cool 👌🏻 And not to ride you, but please Rusty, "water heater"...just saying 😉

[@RustyDobbs]

As you know probably better than me, Bob, if we post it, we own it! I don’t know that I have ever called it anything other than a “hot” water heater! Probably too old to change now! Better than when I referred to spinning a “bolt” onto a threaded rod a couple of times in one of my more popular videos. Heard about that from a bunch of folks! Yeah, if you are interested in 3D and animation, Blender is a good choice these days. The software is free and has an interesting funding model that should keep it always free. I was a long time SketchUp user but dropped it a couple of years ago. No reason any longer for what I do to keep paying for SketchUp. Pretty good learning curve for Blender as with SketchUp, in my experience. Let me know if you get serious and are looking for some tips on getting started. Hope all is well with you!

[@thomasparker1789]

This is a super video - I learned a lot. Question: could a person use an on-demand water heater in a distant bathroom rather than running new pipe back to the water heater? That is to say running the entire bathroom one one 3/4" inch cold water pipe?

[@RustyDobbs]

Thanks for watching and for your comment, Thomas. The simple answer to your question is yes, but as I'm sure you are guessing, it is not without some potential pitfalls that relate to volume of water available and pressure in the lines. But, sure, one 3/4" cold water supply could feed a water heater and hot water lines as well as supplying water to cold water lines. If it is for a master bath with two sinks, a tub and a shower, it would work but probably not very well!

[@robertbdesmond]

You should have called a leak detection company. They would have found the leak precisely and then you could decide whether to open up the floor or re-plumb. This happened to my daughter yesterday. Leak detection cost $600 on a Saturday morning. Plumber came and drilled and Jack hammered the slab floor. The carpet and pad was destroyed by the water leak, so we tore it out. Once the floor was cut out, 2’x2’ square, we found the leak immediately and made the repair. Turned out to be the Heat Recovery Unit hot water feed, so we really did not need it as it could be easily bypassed by shutting off the flow valve at the hot water heater. Total cost $1,100 on a Saturday. The 5,000 square foot 4 bathroom house did not need to be re-plumbed which would have cost around $8K-$10K running new lines through the attic of this massive house, as you did in this video. Leak repaired, thousands $$$$ saved. House is plumbed with CPVC and is only 20 years old. All I have to do is patch the concrete floor, about 2 hour job, tops. I learned a lot in the process, as the leak detection company taught me a lot.

[@RustyDobbs]

Thanks for telling your story about the leak at your daughter’s house, Robert. People checking out this video will benefit from your experience which is more common than realize. Water leaks are something you don’t think about until it happens to you. At the 10 minute mark, I relate that I had my brother in law call two leak detection companies first thing when the leak was discovered. This was a Friday and the earliest either could come out was “maybe” the following Tuesday. The charge just to show up was $500 which would apply toward the cost if they did the repair. Otherwise, that was the cost to try to pinpoint the leak, which was not guaranteed. It was the middle of winter and that was not going to work. Once we began exploring a bit, it was obvious that the leak was under the utility room floor as the wood flooring in one spot was hot. Busting out concrete would destroy the glued down wood flooring and increase repair costs, plus this was the second failure of the copper pipe under the slab so it would be difficult to feel confident that it might not happen again. Since we had bypassed the other leak 15 years earlier, once we opened the wall up again behind the hot water heater a second time, it was obvious what we had done before and a solution to this problem would be relatively simple. We had hot water restored to the bathrooms in a couple of hours and finished the re-pipe to the rest of the house by Saturday afternoon. Total material cost was around $200 and took about 10 hours of work. My brother in law took care of the drywall repairs himself. Obviously, not everyone has access to family members like you and me to help deal with things like this and save them money. The purpose of my video is to inform homeowners of what happens when an under slab leak occurs in copper pipe, most of the time on the hot water side. Copper pipe has been the standard for water line installation for decades and generally thought to be permanent. It is not but it can last a long time. The existence of leak detection companies who are backlogged four days, as in this experience, tells the story. Personal experience in my case as a contractor also says otherwise. There are other choices besides busting out concrete that may be better long term solutions but time, expertise and access are always the problems for homeowners. I have twelve videos on my KZbin channel of projects done for a customer that resulted from an under slab water leak… the third leak that each time flooded their master bedroom floor in a span of two years. I became involved after the third leak which turned out to be about two feet from the second leak. The very frustrated customer wanted to not have another under slab leak. So we re-piped the whole house, hot and cold water, abandoning all pipes under the slab. Two story, five bedrooms and four bathrooms and it was expensive but gave them peace of mind. After that, they decided to remodel all their bathrooms so I was there for a while. Videos on shower floors, barn doors, tile setting, grouting, caulking, etc. all came as a result and actually helped launch my KZbin channel. I’m surprised to hear that CPVC was used under a slab to plumb a house that is 20 years old. I would have assumed it would be copper. Thanks for watching and for your comments, Robert!

[@howtodoitdude1662]

PEX is the way to go. Is your hot water pipes installed in parallel?

[@RustyDobbs]

Yes, Dude, tools have changed things a lot for the better over the years and Pex is a big deal. Copper has always been the gold standard, but time and conditions that cause it to disintigrate create very major problems. I have been surprised at pinholes that develop in copper within maybe six inches or so of circulating pumps and it can happen relatively fast. Must have to do with the electric field created and its impact on copper. I'm not familiar with "parallel" in installing hot water pipes. Was a plumber's helper for only about six months 50 years ago. Must have not been paying attention that day!

[@andrewfield5656]

You just saved my mother in law buying 700k fixer upper, a 55 year old house full of hydronic heat piping

[@RustyDobbs]

Yeah, that sounds like a house that could have lots of surprises and probably few that would be pleasant surprises! Thanks for your comment, Andrew!

[@aaronbaraiya3692]

So basically you rerouted throguh the ceilings and attic? Also any idea why the original plumber didnt go through the attic/celing in the first place?

[@RustyDobbs]

Yes, you do what you need to do to get the water lines to the faucets in the house as easily as possible. The fastest way to install copper water lines in this type of construction is to run it under the slab in the ground which is code in most areas. It's just a mess if you have a leak down the road. These copper pipes lasted about 35 years before a leak ever showed up. Then one more after another 15 years. This method for installing water lines with this type of slab would have been the norm for plumbers 50 years ago.

[@anthonykaiser974]

Looks like a better plan than under slab repair.

[@RustyDobbs]

Yep, Anthony, repairing one spot in copper under the slab doesn't assure that there are not other weak spots somewhere else!

[@Allin1mom]

Hi! I have a question. What if the supply pipes are in our attic and we still have water coming out of the cracks on our slab foundation?

[@RustyDobbs]

That doesn't sound like a good situation regardless. It probably does not have anything to do with the pipes in your attic, but there could be a leak in the water supply line coming to your house that is finding its way to the cracks in your foundation. If you live in an area that gets a lot of rain, you could also be having some groundwater and/or drainage problems with water flowing toward your foundation rather that being diverted away. Good luck.

[@gordonpotts753]

Whatz ur opinion on Pex as it relates to rodent damage. In other words is Pex susceptible to rodent damage?

[@RustyDobbs]

That’s a good question, Gordon! I have not come up against that issue. I would think that typical field mice would have a tough time chewing through Pex. It is flexible but rigid and thick-walled. Now rats, squirrels, etc., may be a different situation. I would think if an animal could get its mouth around the Pex, it might be able to chew through it over time, but it would be a chore! If not, I don't think so. But if it happened and you could access the location, it would be an easy fix. Thanks for raising that question!

[@bv5000]

Where are yaw located we got a hold Neighborhood full leaks in Concrete slab. No plumber wants to touch it said it to much wrk🤷🏾‍♂️

[@RustyDobbs]

Yes, that does not sound good if lots of homes built around the same time in the same neighborhood have leaks under the slab. Doing those kinds of repipes usually puts you in cramped quarters working in tight spaces. You have to have a lot of patience! Patience is one thing most plumbers I have know don't have!

[@tonvand.4601]

Are copper pipes usually running IN the slab or rather UNDER it?

[@RustyDobbs]

Typically, the slabs are 4" thick so the copper passes through the slab and is buried in trenches under the slab that are probably 18" to 24" deep. The copper needs a plastic sleeve installed around it at slab level to keep the concrete from coming in contact with the copper pipe. If the sleeve is not there, the copper will corrode where it touches the cement and leak over time.

[@conchim99]

I got hot spots in my bathroom 2 days ago. In the morning around 5am, i can hear water running under the floor. It is different any other day before this leaking occurs. A few days ago, I was messing with a frozen overflow bathtub last 3 days by pouring in CLR and trying to pull out the valve with my metal rod with a hook at the end but all no avail. The valve is really stuck. I want to remove it so i use my small water jet and push the clog out to the main sewer pipe. My question is could i have damage the hot water pipe with my hook end while i was pulling hard on the metal rod? I could have poke a hole in the pipe and caused leaking hence hotspot ? The hospot is about 2 to 3 feet away from the bathtub. If it is for sure i have a leak, i would like to bypass it with PEX tube. Im a very DIY person and handy. Thank you

[@RustyDobbs]

No, I wouldn’t think what you were doing with the drain would have impacted your hot water leak at all. Those leaks in copper under the slab happen when you least expect it and it is never good thing but it sounds like yours is near the hotspot. It’s common sense that where the floor is warm, the reason is a hot water leak nearby. Hearing the water running tells you all you need to know. If opening up the floor where the hotspot is easy to do and repair you might want to consider fixing the leak that way first. Then maybe be able to plan a bigger project to bypass or repipe the house at a more convenient time because you could still have another leak at a later time. The idea of repiping is not difficult to understand what needs to be done. Doing it, however, is time consuming and labor intensive. You really need to plan it out and think through the process if you can. You will learn a lot doing a repipe and will feel good about it when you are done! Good luck!

[@conchim99]

@RustyDobbs I forgot to tell you. I used water jetter adapter I bought that I can adapt 50 feet of line to my 2000 psi ryobi electric power washer. I snake it into my vent pipe in the roof and came down full blast. Could I have damage the water pipe when I did that? I did it in the past with no problem. No been 3 days. I'm hearing water sound reverberate inside the wall that has water pipe in it. Could this be the source of leaking that lead to hot tile in floor th as is about 3 feet away? Plz look at video. I spoke Vietnamese to my friend who is a contractor in Portland. Thanks I'm stuck at my day job figuring out what to do when I get home.

[@conchim99]

kzbin.infoucYLdCRohKM?si=10ZUjKDczFDs59aH

[@conchim99]

@@RustyDobbs thank you so much for your time

[@slowslug3247]

Wouldn’t the glue down floor start to fail from the moisture in the concrete slab coming up? Don’t you have to dry the concrete now?

[@RustyDobbs]

Yes, if water is actually coming up through the slab, the wood will start to swell and buckle so you will have that problem to deal with and it will be obvious quickly. In this situation, the leak was discovered almost immediately because the water heater was running continuously with no hot water usage happening in the house and the family snapped to what was happening and closed off valve on the water heater. The slab near where we cut the hole in the wall was hot, so we assumed the leak was under the slab there. The ground in our area of the country is decomposed granite and sand so it is really porous. The water typically goes straight down. Now if you have a home on clay, it is a whole other story!

[@antwangiantsdoexist5314]

Is this considered a re-route?

[@RustyDobbs]

Yep, that would be a good description!

[@desertdust8255]

Did you need to pull permits to do this?

[@RustyDobbs]

My guess is that if you asked an inspector, they would say yes, but I don't know that for sure. When it's an emergency situation, I would think they would be more interested in proper materials and methods being used to make the repair over you pulling a permit first to fix a broken pipe. Certainly no reason to make a repair that doesn't meet code after it is completed.

[@FreeAmerican-mm2my]

Could you avoid permits on work inside a house/structure??? Yes. Every city is different, but I have pulled permits for inside repair and they were never inspected. My city is more focused on the $$$ they get for the permit, not in enforcing Code,

[@dashcammer4322]

Couldn't run a water line in an unheated attic here, it gets too cold and local codes thus prohibit it.

[@RustyDobbs]

Yes, certainly really cold climates can be more of a problem but you have to have water. Codes relate more to new construction and remodels, I would think. There is a type of Pex that is designed for very cold locations. If I had no other option, I would be inclined to install heat tapes and insulate the pipes in those harsh environments. Depending on the situation, I might install a second heat tape as a backup if and when the first heat tape failed.

[@user-pe6oz5ok5q]

Jamaican Plumber: You Americans always use copper. No PVC.

[@RustyDobbs]

Copper used to be the standard for decades until Pex came along and was accepted by the regulators but as you know, copper has its problems too. CPVC was generally used in mobile homes. PVC under pressure has always been ok to use in lawn sprinkler systems but not in homes.

[@TheFalconJetDriver]

One thing That I have run across is that plumbers do not neutralize the acid in the flux after sweating a pipe! I make a paste of Baking soda and wipe down the joint after sweating a joint. Today I have a pex crimping tool and that problem is over.and I am not a plumber.

[@RustyDobbs]

Yeah, Falcon, Pex and the tools/fittings available these days make the need to sweat joints less necessary than ever. Took me a few years to completely trust them. I was a plumber's helper for about 6 months fifty years ago, so just learned the basics then, but have not forgotten. Have never heard of neutralizing the acid in the flux, but sounds reasonable. Thanks for your comments!

[@TheFalconJetDriver]

@@RustyDobbs Our house we live in was built in 1960, in the unity room in pin hole leak developed and it was for the very reason that the flux weakened the pipe. In VA I built 3 houses of my own over years doing everything except the HVAC and roofing and the brick work. As an Electrical Engineer the electrical Part was easy as teenager I worked at different times for both a plumber and an electrician. I had both of those contractors look over my work prior to having the inspector come out. It was with the plumber that taught me to wipe down the sweated joint with baking soda and water paste. As for PEX today it is all I will use if I can while living in Stafford County, VA I plumbed in water in each stall of a barn with PEX and during the winter the water would freeze. I never had a pipe break or leak. And that was 13 years ago.

[@TheFalconJetDriver]

A hot water heater? I have a cold water heater. Why would you want to heat Hot water?🤣🛫 I am with you using the push on fitting near the gas line if you were not able to make up that joint anywhere else.