Leak under concrete slab? Where?

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2002sheds

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Hi All,
This forum has been fantastic, so I am hoping that you all can help me yet again :)

We have a rental house that was built in the early 1950s and it has a concrete slab. You probably already know where this is going…

When we bought the house, the living room floor had a bit of a hump in the concrete. I decided to cut out a square of the floor and re-pour it before laying down carpet, and while some helpers were doing demo, we all suddenly smelled gas as we dug out the rubble and some dirt. There was a pinhole in the gas line.

That issue was resolved years ago by rerouting the gas line. Now I am concerned that the cold water pipe has gone the same way… and it probably has, given that at some point the water supply line was repiped all the way around the house and now enters above grade.

I noticed the sound of running water coming from that pipe, but initially wrote it off to the fact that a large family is living there and someone is almost constantly using water. Today, though, I confirmed that there is a leak. I’m able to shut off the supply right where it meets the house (in back), so I am confident that the issue is not between the house and the street. I then confirmed that every valve that I could find inside the home was shut off, but still could hear running water.

I have called a professional to come over on Monday, but I am wondering if there are ways for me to check it myself in the meantime…?

And if I decide to re-route and re-plumb with PEX, are there any tips that you can share? In addition the slab, this house has a nearly flat roof, so not a lot of touting options that are clear to me…
 

Terry

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For repiping, you will need to count up the fixture units and with the proper chart, measure backwards to the main water supply.
How many bathrooms?
You will want the pipes below the roof I would think. How cold is Santa Rose in the Winter?
"Over the course of the year, the temperature typically varies from 37°F to 84°F and is rarely below 28°F or above 96°F."

In the Seattle area I prefer to keep all the piping below the ceiling. If I have to run it above, I like to put a blanket of insulation over the pipes trapping the warmth from the interior of the home.

Finding leaks in slabs we use "leak detection". They have a way to listen to the sound the leak makes and can mark their best guess.
 

Jeff H Young

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70 year old house you might want to save your money spent on detection and repipe it so basically who cares where the failed pipe is? of course there are times where you want to pinpoint you decide whether you want to pay for that knowledge.
Sometimes I hate to say but depending on the job a pipe can neatly run exposed across a ceiling( Preferably just a closet) its a rental maybe a little funky so you do what you gotta and re- rout later when house is empty or you are remodeling it doesn't have to look bad. not everyone wants to rip walls tile , maybe even some sort of wood work, you might even consider a tight soffit kinda like a crown molding to cover .
 

2002sheds

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For repiping, you will need to count up the fixture units and with the proper chart, measure backwards to the main water supply.
How many bathrooms?
You will want the pipes below the roof I would think. How cold is Santa Rose in the Winter?
"Over the course of the year, the temperature typically varies from 37°F to 84°F and is rarely below 28°F or above 96°F."

In the Seattle area I prefer to keep all the piping below the ceiling. If I have to run it above, I like to put a blanket of insulation over the pipes trapping the warmth from the interior of the home.

Finding leaks in slabs we use "leak detection". They have a way to listen to the sound the leak makes and can mark their best guess.
Hi Terry,
Thanks very much for the response — I appreciate it!
I should’ve better described the house. The water currently comes into the house near the kitchen (cold water for the kitchen faucet is branched off of that pipe). From there my best guess is that the cold line resembles a capital T, where the left side is where the faucet is for the washer and the water heater, and the right side is the one bathroom, with one sink and tub/shower.
Repiping sounds like it will be difficult, as there is not access below (slab floor), and there is not an attic. One thought that popped into my head was to install a tankless water heater on the side of the house near the bathroom, making those runs quite short (while still having to deal with no attic space, since this house has a flat roof). I would then plumb the kitchen and laundry via the joist cavities on that side of the house. The challenge on both sides is traversing multiple joist bays.
Thoughts? Other ideas? I am definitely open to all.

Thanks,
David
 

Jeff H Young

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There's tons of different things you can do besides what I already named you can remove drywall at ceiling, you can saw cut floor, you can trench around house and pop through wall to house you can do a combination of several . Also you can go with what Terry mentioned and get a leak detector and patch the pipe might get several more years is it copper or galvanized. just a cheap house that you are ready to sell at top of the market? or something worth putting money into? Each client has different needs and expectations. Fitter30 has good ideas that's what I'm talking about there is no book on every job these might work or lead you to come up with Idea.
 

2002sheds

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Hi Fitter, Jeff,
Fitter, I will definitely check out the line covers — thanks!
And Jeff, to answer your questions, this is a early 1950s house with original touches like the the tile in the bath and kitchen. We’ll probably hang onto it for some time…
I agree that there are many ways to get this solved. Since the water supply had already been re-routed (maybe because of a similar issue?), along with the gas line, I am concerned that any repair involving breaking through the concrete will only delay the inevitable— and I don’t know if that would be for days or years… since the home is currently leased for a year, I definitely have to figure this out and soon. Having original tile on the walls and floor of the bathroom does not make it any easier.
A plumber that I have used for different jobs returned my call a short time ago. His advice is to definitely re-pipe, but he rejected my suggestion of keeping the existing water heater to service the laundry room and kitchen while still going forward with the idea of hanging a tankless water heater on the outside wall near the bath (other side of the house, but both the gas and water supplies are right there).
My thinking is that he is onto something, in terms of his suggestion that I remove the siding near the bath to allow an approach to the sink and toilet through one wall, and past the tub and to the wall upon which the shower valve is mounted.
What I am less clear about is the other areas (kitchen and laundry area with water heater)… I can access the joist bays from both the laundry room and at the point where the exterior wall meets the top plate. I was thinking that I could run PEX down through the wall cavity near the sink, with a tee for the cold water. Once the PEX is in the laundry room, the pipes can be left exposed and the connections would be less complex.
Thoughts? Opinions?


Thanks,
David
 

2002sheds

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Hi Fitter, Jeff,
Fitter, I will definitely check out the line covers — thanks!
And Jeff, to answer your questions, this is a early 1950s house with original touches like the the tile in the bath and kitchen. We’ll probably hang onto it for some time…
I agree that there are many ways to get this solved. Since the water supply had already been re-routed (maybe because of a similar issue?), along with the gas line, I am concerned that any repair involving breaking through the concrete will only delay the inevitable— and I don’t know if that would be for days or years… since the home is currently leased for a year, I definitely have to figure this out and soon. Having original tile on the walls and floor of the bathroom does not make it any easier.
A plumber that I have used for different jobs returned my call a short time ago. His advice is to definitely re-pipe, but he rejected my suggestion of keeping the existing water heater to service the laundry room and kitchen while still going forward with the idea of hanging a tankless water heater on the outside wall near the bath (other side of the house, but both the gas and water supplies are right there).
My thinking is that he is onto something, in terms of his suggestion that I remove the siding near the bath to allow an approach to the sink and toilet through one wall, and past the tub and to the wall upon which the shower valve is mounted.
What I am less clear about is the other areas (kitchen and laundry area with water heater)… I can access the joist bays from both the laundry room and at the point where the exterior wall meets the top plate. I was thinking that I could run PEX down through the wall cavity near the sink, with a tee for the cold water. Once the PEX is in the laundry room, the pipes can be left exposed and the connections would be less complex.
Thoughts? Opinions?


Thanks,
David
After getting a bit of much needed sleep, I may have gained some clarity… when I was checking to see if everything was shut off, I did turn off the supply to the water heater. I am also pretty sure that the water heater was not running for any of the time I was searching for the leak.

This is giving me the hope that only the cold side is leaking at present. While it is only a matter of time until the buried hot side pipes leak as well, I may be able to provide a solution that is much quicker, at least for now (with 7 people living there, as soon as possible is preferred).

The cold water supply coming from the street wraps around the house, hugging the foundation as it travels all the way to the back of the house to the kitchen. On the path, it passes the bathroom (this is a single level house with only one bath). While my copper soldering skills are not finely honed, they could be strong enough for me to install a tee fitting to go into the wall, transition to pex and supply the toilet and cold water side of the sink, and another to go into the wall, transition to PEX and travel past the tub/shower to provide cold water to that valve.

I could then do a similar option at the back of the house, starting with a tee for the cold water side of the kitchen sink faucet and then making a bee line to the laundry room. Once there, the PEX can be hung on the wall, as the galvanized pipe currently is.

I realize that this is temporary, but it occurred to me that the systems are slightly different and that I can use that difference to my advantage, at least for now.

And when I route the pipes through the walls, I will also pull the hot water PEX lines, so when the day comes that the hot water pipes leak it will be an easier install…

As always, I welcome any feedback!

Thanks,
David
 

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Anytime I do a repipe, I like to change out as much as I can, as whatever gets left behind becomes a job for another day, and more detective work to figure out what went bad this time. It's a good time change out shower and tub valve, change them to single handle and balanced for safety. PEX is a nice way to go, soldering in old homes with the water off you would need a way to put out a fire quickly very close to you. Old wood lights up very quickly.
 

2002sheds

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Anytime I do a repipe, I like to change out as much as I can, as whatever gets left behind becomes a job for another day, and more detective work to figure out what went bad this time. It's a good time change out shower and tub valve, change them to single handle and balanced for safety. PEX is a nice way to go, soldering in old homes with the water off you would need a way to put out a fire quickly very close to you. Old wood lights up very quickly.
Hi Terry,
Thanks very much! I agree about using PEX. My plumber said PEX is not approved for exterior use, but I wonder if that extends to transition fittings like Sharkbite (like I said, my copper soldering skills are a work in progress)?

I will definitely rough in the hot water lines in whatever holes I open up, and there is no doubt that the absolute best path forward is to change it all out, but I am also dealing with the competing interest of speed. With 7 people living there, days (or even hours) without water is a really big deal…

Do you have an opinion regarding the one tankless water heater versus the split setup (new tankless for the bath, existing water heater for laundry and kitchen) I am proposing? I’m thinking ahead…

Thanks Again!
David
 

Reach4

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There are press copper fittings, and there are hand tools that are a lot cheaper than the power tools.

If your repiping could be part of a renovation that adds a second bathroom, that could make your property more valuable for leasing.
 

Jeff H Young

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When it comes to temporary solutions to accommodate residents you might have to leave PEX exposed for days or week if need be. Good idea running a future pipe for when the time comes to do the hot line
 

2002sheds

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There are press copper fittings, and there are hand tools that are a lot cheaper than the power tools.

If your repiping could be part of a renovation that adds a second bathroom, that could make your property more valuable for leasing.
Hi Reach, All,
I just returned from the rental house, and I am more confused than ever. Here is what I learned -- some of this info may be completely irrelevant -- that's how confused I became...

There are two valves that shut off the water at the house. The one out front, on the pipe from the street, and the one in back, which is at the end of a long run of copper and is clearly part of a replacement setup (if there was a line that once ran under the house, it is no longer in service. Both are fairly old valves, with the circular handle.

The valve out front shuts the water all of the way off.

The valve back by the kitchen shuts the water almost all of the way off, but not completely. I put my ear to the copper after closing the valve and I could still hear water running. I then turned the water back on, and all fixtures off.

All the way across the house, I pulled the cover off of the toilet, and while I could not see any water seeping into the fill tube, I could barely hear running water. I then put my ear to the top of the toilet tank fill valve, and slowly turned off the valve at the wall. The noise stopped.

Thinking that I had found the leak, I went back to the valve outside. I could still hear water running (while the toilet supply was off)... bummer !

I then went back to the water heater and put my ear to the tank. I could hear water running, so I turned the valve to close it. The sound went almost completely away, but not all of the way.

The confusion that has set in is that I do not know if there are multiple leaks, or even how far the sound travels when there is a leak. I feel like it will be a good move to put in a new fill apparatus and flap for the toilet, and also to replace the old valve on the copper pipe at the back of the house by the kitchen (so that I can confirm that the leak is not between the valve at the front of the house and the back of the house), but I am starting to feel as though I can't see the forest for all of the trees...

I even feel like replacing the shut off for the cold water that goes into the water heater, but (back to the "how far does the sound travel?" question) the fact that I could hear running water at the water heater at all after no obvious recent hot water use concerns me in itself... and makes me wonder if there is a chance that the leak is on the hot water side. With 7 people there, someone is nearly constantly using hot water. My head is spinning again...


Thanks,
David
 

2002sheds

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when it comes to temporary solutions to accomadate residents you might have to leave pex exposed for days or week if need be. good idea running a future pipe for when the time comes to do the hot line
Hi Jeff,
Thanks for the response! I was referring to the idea that I would use pex to directly transition from the copper, but my plumber corrected me on that mistake immediately...

Thanks,
David
 

Reach4

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Thinking that I had found the leak, I went back to the valve outside. I could still hear water running (while the toilet supply was off)... bummer !.
You may have good hearing in a quiet neighborhood. If you turn off the front valve, do you still hear water-moving sounds at the valve? Maybe the sound is being conducted from the water flowing in the main.

Check your water meter for a sensitive leak detector indicator.
 

2002sheds

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Thinking that I had found the leak, I went back to the valve outside. I could still hear water running (while the toilet supply was off)... bummer !.
You may have good hearing in a quiet neighborhood. If you turn off the front valve, do you still hear water-moving sounds at the valve? Maybe the sound is being conducted from the water flowing in the main.

Check your water meter for a sensitive leak detector indicator.
Hi Reach,
I do not hear water moving in the valve at the back of the house after shutting off the front valve.

Thanks,
David
 

2002sheds

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Hi Reach,
I do not hear water moving in the valve at the back of the house after shutting off the front valve.

Thanks,
David
I’m just wondering now if it is worth it to replace those valves, or if it is almost a waste of time and money…

Thanks,
David
 

Reach4

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Hi Reach,
I do not hear water moving in the valve at the back of the house after shutting off the front valve.
Did you understand that I thought it possible that the front valve successfully shut off the flow, but the sound you heard up front was from flow that was not via the valve? I am not saying that my suspicion is right. I am not a pro.
 

Jeff H Young

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I’m just wondering now if it is worth it to replace those valves, or if it is almost a waste of time and money…

Thanks,
David
One way to check for leaks in places you can't see is to monitor the water meter if it spins your using water
 
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