Dead leg (capped water line)


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Old 04-12-20, 10:43 AM
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Dead leg (capped water line)

I am installing a new double shower and running 1Ē copper about 70 foot from where the main comes into the house to the drops in the attic for shower. Considering the house is 35 yrs old and has underground supply lines I am considering running new plumbing in the attic for this shower. My questions is will the old plumbing under the slab be a problem since I will cap it in the walls? I know Iíll have a dead leg not sure of the length but just donít want bacteria growth to be an issue considering my kitchen and 2 more baths are still connected under slab.
 
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Old 04-12-20, 01:44 PM
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Welcome to the forums.

You have an under slab water line feeding several locations and you want to block one off.
That's fine and won't affect the others still in operation.

Don't know where you are located but water lines in an attic are not recommended.
 
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Old 04-12-20, 02:49 PM
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Many are not concerned by it but there is a potential for problems with dead ended water lines.
The issue is legionella and similar bacteria becoming aerosolized in a shower.
Domestic hot water tanks that are above 125 deg F. will kill these bacteria but the cold water that is introduced into a shower water mix can carry this bacteria and make it airborne to be inhaled.

It would be good to disconnect the dead lines if you can.
 
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Old 04-12-20, 02:50 PM
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Iím located in South Louisiana, I had a friend tell me it was a bad idea to cap the lines off in the wall just above the concrete. Told me many reasons, one stuck in my head was stagnant water. However neither me or him know anything about this. Other than the possible leak why would it be a bad idea for plumbing to be located in the attic considering the hot water heater is located there, if you donít mind me asking?
 
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Old 04-12-20, 02:52 PM
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Looks like my post was too soon! 😊
 
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Old 04-12-20, 03:00 PM
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Thatís no problem, I was replying to the other post when your post come through Greg. I had heard about the legionella and bacteria, itís just the issue is I would have to bust concrete up and find the line to cap or re- plumb the whole house which really is t what I wanted to do. Seems like a small make the shower bigger project has turned into its own nightmare.
 
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Old 04-13-20, 12:48 PM
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You didn't originally post your location.
Many people in a possible freeze area run plumbing thru an attic.
 
 

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