Domestic Water Plumbing in Cold Regions (northeast)

[NS4U]

I live in Massachusetts where (at least on the structural side of things) we need to bury foundations deep enough so that they are below the freeze line of the soil.

I assumed (perhaps naively) that there would be something similar for domestic water supplies. For example, say a water branch from the main in the street to my house has to be buried “X” feet below grade.

I reviewed the mass plumbing code and couldn't find any sort of requirement. Am I just missing something?

I ask because I have slab-on-grade (there are no freeze walls around the perimeter-the house is kind of old), where the domestic water line burst under the slab this weekend. To minimize disturbance, the plumber came in and ran a new branch from the main, and turned the branch up just inside of the exterior wall, then connected the water supply. I've attached a sketch that hopefully illustrates the repaired scenario I have now.

My concern is that where the pipe turns up, it is too close to the ground and could potentially freeze.

What are your thoughts? Is this addressed in any codes?

 

[NS4U]

Here's the sketch

 

[ornerynorsk]

I don't know how cold you get out East, but the short answer, I believe, is yes. You may find that on bitterly cold days and nights that the water may need to be left on a slow drip.

In my town, much of the residential area has a foot or two of earth over native bedrock, and many waterlines are literally a foot to 18 inches below the surface. We routinely reach 30 below in the winter.

The residual heat from the house will help somewhat, but there's no way to say for sure one way or the other what will happen in your case. You could always bury a heat tape with the line as far down as you're able to get.

Good Luck.

 

[MTPipeliner]

Can't help you with the code issue, but I think you may have a potential to freeze the line.

A friend of mine had a similar issue last winter and after getting it thawed out he left a tap on all winter. This past summer he dug it all up, put a heat tape on it and also burried some insulation on top of the line. As far as I know he hasn't had any trouble this winter, but we're just now getting real cold.

I think he ran into trouble in the -15 to -25 F range.

 

[TenPenny]

I thought most plumbing codes called for the line to be 6 or 12" below frost level, but I could be wrong.

 

[MiketheEngineer]

In St. Louis I think the local code is 36'' below grade. Most houses have basements and it comes in at that level. Also - we don't usually see that much COLD - except tonite it is going down to -2F. I have seen -15F here once.

It is something that must be considered as noted above and those solutions seem reasonable.

 

[vpl]

In the Chicago area, I believe domestic piping needs to be 48" below grade or freeze protection needs to be installed.

Patricia Lougheed

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[zekeman]

I think you may have a problem here, but I would also let the plumbers take a crack at it. Sometimes their experience trumps heavy analysis in these cases.

http://ths.gardenweb.com/forums/plumbing/

My own take is there is a 2 fold problem
1) is the depth of horizontal pipe sufficient
2) the potential for freezing of the vertical part

I have 2 questions;

How close is the vertical pipe to the inside wall?

What was the lowest temperature of inside the enclosed space in your experience?

If you have or can borrow an IR thermometer, maybe a reading of the pipe inside the wall on a cold night might shed some light on the problem. And it would help to get readings at the horizontal depth of pipe.

 

[rconner]

Don’t know specifically about your local or other “plumbing codes”, but I do know there are many specifications that speak to things like this. A recent version of the Ten States Standards e.g. accessible at

http://10statesstandards.com/waterstandards.html#1.4

includes the guidance under Sec. 8.7.3 Cover

“Water mains shall be covered with sufficient earth or other insulation to prevent freezing.”

[A topographical-appearance map of “Frost Depth” over the United States is incidentally also included I guess for similar reference in ANSI/AWWA Standard D100 for Welded Steel Water Tanks.]

I guess if anything, at least if home plumbing is not leaking or left dripping, plumbing/service lines might be even more subject to freezing than larger properly looped and circulating water distribution mains, due at least in part to different physical properties,

the angle the service lines are often tapped goose-necked (down) into the mains, and the dead-end nature of most service lines (and the fact that homeowners are not always home and drawing water)!

[If one doesn’t like the substantial depth that sometimes results, of course maybe Algore and ilk (incl. Legion of co-inventors and like minded “scientists”?) could be convincing that one doesn’t now need as much as one used to??]