In my basement I have a 1/2" copper water pipe that goes to an outdoor faucet for a garden hose/sprinkler. This line has its own shutoff, so during the winter it is turned off and emptied.

The problem is that about 15 feet from the exterior wall the pipe reaches a critical junction in the water lines. If it gets really cold outside, below 10F, the pipe will transmit the cold all the way to this junction and freeze it and then the water supply to the whole house is cut off. I have used heat tapes, propane torches etc to solve the problem when it crops up, which is once every 5 years or so.

However, what I would really like to do is install a passive (non-energy-using) solution to get rid of the problem permanently.

What I envision doing is installing some kind of thermal isolator in the line to the faucet. So, for example, if I replaced say a 12" length of the pipe with a PVC pipe it would probably solve the problem because the PVC will not conduct the cold nearly so well as the copper, so basically the PVC should "thermally isolate" the faucet. That's my theory at least. Another option would be to create a removable link or section in the pipe. The section would be removed/disconnected in the winter, then connected back up again in the spring.

Is there a way to do either of these things?

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    I think you need to look for some other culprit here. I'd be really very surprised if the empty copper pipe is conducting enough heat to freeze pipes 15 feet inside of the basement. We get much colder here (-15F) and I have a typical sillcock, with a shutoff at the junction that doesn't freeze upstream connections only 2-3 feet away in my crawlspace, even when I'm using the wood burner extensively (so the furnace in the crawlspace isn't running). Commented Jan 9, 2015 at 18:55
  • @CoAstroGeek That is, indeed, what is happening. The basement is pretty cool (about 55 F typically) to begin with, since it is unheated. I can actually measure the temperature along the copper line using the bulb of a thermometer so I know that is what is happening. The cold is actually creeping down the pipe until it reaches the junction. Commented Jan 9, 2015 at 19:25
  • I'm sure my crawlspace is no warmer. 15' is a long way in a 55 degree space - I've never seen empty pipes conduct enough heat to freeze stuff even a few feet in. If that were the case, all the plumbing underlying my kitchen & bath should freeze solid. Are you sure it's freezing there and not someplace else upstream? Commented Jan 9, 2015 at 19:32
  • @CoAstroGeek Look, I know what's happening. There is a big metal spigot on the outside of the house that is acting like a cold sink. The pipe connected to that faucet is then transmitting the cold to the junction. If I heat up the junction with a propane torch water starts flowing again, its that simple. This only happen happens if it gets crazy cold outside, like below 10F for 24 hours or more. Commented Jan 9, 2015 at 19:37
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    I'd agree with CoAtroGeek. It's currently 2 degrees where I live, and I have a metal spigot outside. It gets colder than 55F in my basement. Crazy cold here is -25F, and it certainly got that cold last winter for several hours. We have days where it never gets above zero the whole day. I've never had problems with a spigot leaking enough heat to freeze a junction, and there's no heat tape or insulation around the pipes. The junction is perhaps 10 feet away. So I'd say your problem is the air getting cold, not the copper leaking heat outside.
    – user30371
    Commented Jan 10, 2015 at 6:50

2 Answers 2


I agree with the comment in that its surprising the copper pipe would conduct enough heat to freeze the downstream pipe, are you sure there's not a draft or something like that?

Your idea to isolate the pipe seems relatively sound though. You would likely want to use PEX instead of PVC. PEX normally requires a special tool to crimp the connectors, so I would recommend using a SharkBite push-in coupling fitting to connect the PEX to the copper and vise versa as these don't require any special tools to install.
SharkBite coupling

From http://www.sharkbite.com/product/couplings/

SharkBite is the Push-Fit connection system that is really taking hold. It’s the easiest way to join copper, CPVC or PEX pipe in any combination with no soldering, clamps, unions or glue. Just insert the pipe and the stainless steel teeth bite down and grip tight, while a specially formulated O-ring compresses to create a perfect seal.

I don't have any affiliation with SharkBite, they are just a well known brand of push-in fittings. Your local store might have other brands too


Get yourself one of these faucet insulation covers.

enter image description here

The stretchy cord on the inside has a loop or hook that grasps the faucet handle. You then press the foam insulator cup over the faucet with the foam seal against the house wall. The foam is thick enough that it is able to conform over an irregular wall surface such as a lap type siding. Then the squeeze clamp is moved down the cord which is slightly stretched. The clamp goes against the outside apex of the faucet cover. The stretch of the cord holds the cover securely against the house wall.

Here is a picture of a typical installed cover.

enter image description here

This will surely solve your problem in the easiest way. The cover keeps outside cold air from causing the faucet to be the extreme cold sink. As a matter of fact the piping may well conduct heat from inside the dwelling to the faucet helping to warm the inside of the foam cover.

Best thing of all is that these covers are inexpensive.

Word of advice

Steer away from faucet covers that use a hard plastic hook with a plastic wing nut. These are a pain to use because of several factors. 1) The hook is often short and hard to get hooked onto the faucet and hard to unhook in the spring. 2) The plastic threaded hook bolt takes forever to thread the wing nut down two to three inches of the bolt while you try to hold the cover in place and keep the hook to stay hooked. 3) The plastic threads are really cheap and (especially ones with a plastic wing nut) can easily cross thread or become stripped out.

enter image description here

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