Running water at night when temperatures are below freezing

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I’ve been told to run the faucet furthest from the water meter at a slow trickle at night to prevent the pipes in our two story home from freezing (it’s about 5 degrees F where I am). Why do they recommend doing this at night only and not during the day—for example, when you’re away at work? If the temperature is below freezing both periods what is the difference? Wouldn’t you want to do this day and night?

In: Physics

22 Answers

Anonymous 0 Comments

> Why do they recommend doing this at night only and not during the day—for example, when you’re away at work?

Usually it gets colder at night. You know, with the lack of sun.

> If the temperature is below freezing both periods what is the difference?

Colder temperatures can resulting in freezing temperatures penetrating deeper into your structure than otherwise. For example pipes in an exterior wall might freeze only when the outside temperature is well below zero as otherwise the interior of the wall remains warmer than freezing.

Anonymous 0 Comments

It is not necessary to run the water constantly, just frequently. The underlying assumption is that normal usage during the day will run the water enough, but at night there is basically no activity AND it gets colder, so it becomes necessary to leave a little bit of flow to prevent water freezing in the pipes.

Anonymous 0 Comments

In addition to the temperature difference between day and night, you also use your pipes more frequently during the day. Cleaning dishes, pouring water into cups, brushing your teeth, etc. Whereas at night, the pipes would be sitting “still” for 6-8 hours.

Anonymous 0 Comments

Running water don’t freeze as easily as standing water.

If water freezes in your pipes, there’s a good chance it will burst and flood your house.

Anonymous 0 Comments

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Anonymous 0 Comments

I had a small half bath with the pipes in the wall (north facing, so no sun during winter here in Massachusetts.)

Every year when it got to single digits we would leave the faucet dripping to prevent freezing.

We had the pipes relocated so they are interior, but, they come up through an old section of porch so even today when it gets to single digits we have to leave it dripping.

Luckily it only happens a few nights a year.

Probably frozen three times in the past 10 years….always worrisome.

Anonymous 0 Comments

Moving water is harder to freeze, it’s as simple as that. No one wants water freezing in their pipes since there is no where for the water to expand to so the pipe can burst.

Anonymous 0 Comments

Water pipes are always filled with water. When you use appliances, that water moves slightly which makes it harder to freeze.

Because people are smart, they design water pipes with a certain level of insulation so that the pipes won’t freeze during more “normal” temperatures. But because it gets much colder at night, the temperatures are more likely to reach a level that the insulation can’t handle which would lead to frozen/burst pipes.

Anonymous 0 Comments

The assumption is that it’s colder at night and you will be using water intermittently during the day. If it’s staying really cold during the day and you’re away at work for 8 hours, I’d trickle it during the day too. 

Anonymous 0 Comments

Most people here have it mostly right.

Flowing water does freeze slower. What is missing is that the water in your house is under pressure so it sits still, when it begins to freeze the expanding ice stays in place, thus bursting your pipes. When you drip your faucet, you’re giving the place for the ice to expand into.