How cold to freeze pipes?

[California]

This is a mild climate. Nobody prepares for a freeze because they only occur 1-2 times in a decade.

I'm worried! The forecast predicts 56 degrees high, 25 degrees overnight low for the next couple of days.

I don't think I have any vegetation that would be harmed but I'm worried about outdoor water pipes. The plumbing includes runs up the water tower (no longer in use, but live) and under the eaves of the barn down to a valve for loading the orchard sprayer, all fully exposed. Plus the garden faucets typically stick 3 ft straight up out of the ground. You guys in the colder climates wouldn't build like this but here its common.

Is this 56 hi/25 low cold enough to burst pipes?

 

[Bird]

Is this 56 hi/25 low cold enough to burst pipes?

I think it will depend on how long the temperature stays below freezing. If it were my pipes, I'd probably worry about them, even leave water dripping, if possible, even though I actually think the odds of having any damage are pretty slim.

 

[CharlieTR]

I was also worried a lot last year when it got down to 15 ot 16 for a few days. My copper pipes are under a crawlspace foundation and only have that black foam covering them. When I turned on the water it felt like freezing to me. I just let the water drip a little, the main line did freeze about 5000' down the road that week.

Anyway I would think 25 is not cold enough, unless it stays that way and no water flowing. The water in a specific section of the pipe would need to get less than 32 all the way though and freezing does not automatically mean busted pipes. I would let it drip a night and cover pipes if possible.

 

[EddieWalker]

Like Bird said, it depends on how long it stays that cold. If it's just an hour at first light, you might be ok.

To be on the safe side, I'd let it drip all night long. I'd also try to cover them with something. Just a sheet of plywood leaing against the wall will offer some help. Maybe stuff a towel or some old sheets around them? I have a bunch of old blankets that I use for painting that I'd use for something like that.

Last winter we had only lived in our home a few months and I didn't have the outside stuff all done when we had a few days that got down to 17 degrees. It froze the water in my backflow device, leaving us with no water for showers in the morning. Steph had to go to her moms house to bath. hahaha

Anyway, I put some sheets of plywood over the valve and left them there all winter long without any more problems even though we had plenty of days that were just as cold. Now I have a small box built over it that looks nice.

Good luck,
Eddie

 

[MossRoad]

25 is cold. The water in my garden hoses freezes solid at less than that overnight so I would imagine that a metal pipe would be no different. It does not take much to burst a copper pipe. Iron pipes will take more abuse. I would either drain them back to underground or leave them running overnight. Draining is best, but a trickle of water should keep it from freezing if it is just going to be below 32 for several hours.

 

[California]

OK so far.

The weather station at the airport is what the forecasts describe. They had a low of 26.

However there is an amateur station, one of those 'Other Local Observations', a half mile from me. We are up on the ridge 300 ft higher than the airport. He showed one reading of 32 and the rest 33 or better.

Now I know a little better what to predict. Thanks to all for the comments!

 

[Dusty]

25 is cold. The water in my garden hoses freezes solid at less than that overnight so I would imagine that a metal pipe would be no different. It does not take much to burst a copper pipe. Iron pipes will take more abuse. I would either drain them back to underground or leave them running overnight. Draining is best, but a trickle of water should keep it from freezing if it is just going to be below 32 for several hours.

I have found that copper being softer has more give before it cracks from freezing that iron pipes. Once the water freezes solid in the iron pipe, it seems that it always cracks. Our bathroom toilet water line has frozen every year for the past 20+ years for about a week every time the temperature drops into the minus numbers. It has never cracked. I have been unsuccessful in finding the section that freezes to prevent this. I know it is in the wall somewhere, but where I have no idea. Just one of those problems that you try to avoid while building, but seem to happen just the same.
Dusty

 

[MossRoad]

I have found that copper being softer has more give before it cracks from freezing that iron pipes. Once the water freezes solid in the iron pipe, it seems that it always cracks. Our bathroom toilet water line has frozen every year for the past 20+ years for about a week every time the temperature drops into the minus numbers. It has never cracked. I have been unsuccessful in finding the section that freezes to prevent this. I know it is in the wall somewhere, but where I have no idea. Just one of those problems that you try to avoid while building, but seem to happen just the same.
Dusty

Hmm. We had copper pipes inside the house to a shutoff valve, then an iron stub going through the wall, then the spigot outside the house. A few years we forgot to close the shutoff inside the house and drain the steel stub. The copper split open before the shutoff inside the house on several occassions. After about the third or fourth time my dad had enough and had the spigots changed out to the ones that actually shut off the water a foot inside the house. That solved the problem.

 

[Dusty]

The one thing that I forgot to mention is that copper comes in various thickness. M being the thinest, L being what is normally used, or at least it used to be before the copper prices skyrocketed, and M being the heaviest. I piped the house with M in the walls, and L in the open areas of the cellar. I have frost proof wall hydrants for all outside water use.
Dusty

 

[Egon]

If you are really worried apply some " Heat Tape "