Why is it bad to leave water running

After so many hard freezes this winter, we've got the drip-the-water drill down on nights when the forecast calls for plummeting temperatures. But why exactly does that work? And do you really need to drip both the hot and cold faucets? Will a few dribbles from the pipe suffice, or is the pencil-thin stream a must?

Índice Show

Do You Really Need to Drip Faucets When the Temperature Dips Below Freezing?
Yes, you actually do—and it could save you trouble in the long run.
Yes, You Should Drip Your Faucet in Cold Weather
At What Temperature Do Pipes Freeze and Burst?
How to Thaw Frozen Pipes
How long should you leave the water running?
What will happen if we keep the water tap running for a very long time?
Should you leave water running so pipes don't freeze?
Is it bad to leave faucet running?

As we brace for yet another winter storm, I called William B. Rose, an architect and senior researcher at the Illinois Sustainable Technology Center at the University of Illinois, Urbana-Champaign. Rose and fellow senior researcher Jeffrey Gordon spent two years back in the mid-1990s researching the affects of freezes on plumbing.

Reached on Monday afternoon at his office in Champaign, Il., -- where the temperature was hovering about 7 degrees and was predicted to drop into the "minus teens tonight and tomorrow," he said -- Rose outlined the facts about burst pipes. An edited transcript of our conversation is below.

Q: My husband and I have been debating whether we could get away with just running the cold water. Is it important to run the hot, too?

A: Yes, in fact, if you contact plumbers who repair pipes following a freeze, they're likely to say 70 percent or more of the pipes they repair are the hot water pipes.

You have to understand the way pipes burst. If the pipe is surrounded by cold air, especially cold wind, it will start ice growth. The ice grows from the wall of the pipe inward, until it reaches blockage, then ice grows along the length of the pipe. That growth along the length of the pipe acts like a piston that elevates the water pressure in the pipe. It's the pressure that causes the rupture.

Q: So why does that mean hot water pipes are more likely to burst?

A: It's the toilet. Often you have one line that feeds a bathroom: the tub, toilet, lavatory all coming off the same line. If you imagine pressure building up in the water line, all it has to do is force the ball float to go down a little (in the toilet tank), allowing water to dribble into the tank, relieving the pressure on the cold water pipe (The hot water pipe doesn't have that relief).

Q: Do you need to keep the water running in a pencil-thin stream? Or will just a drip work?

A: It doesn't matter how fast the drip is. The slower the drip, the less water wasted. The rupture is due to the pressure. If you have some kind of pressure relief (by leaving the faucet open), the (ice) piston can keep on pushing but nothing will rupture.

Q: Should you still run the water if you've insulated your pipes?

A: An incomplete insulation job is probably worse than no insulation. If you're using the foam tubes, you have to look very closely at what's happening at the plumbing fittings, the elbow or tee. Lots of times, people will put the tube on the straight section and leave the fittings exposed. You really want to protect the whole pipe and fittings. If you do that, you're probably OK in Louisiana."

Q: Our weather reports always talk about hard freezes and light freezes. When should you worry about your pipes?

A: It's not just cold temperatures, but cold temperatures blowing on the pipe. The wind is the real kicker. Protecting against drafts is really the key.

Do You Really Need to Drip Faucets When the Temperature Dips Below Freezing?

Yes, you actually do—and it could save you trouble in the long run.

Published on January 21, 2022

As the winter season continues to sweep through the South, your main concern right now might be avoiding the typical beauty mistakes that could be ruining your skin. Though exfoliating weekly is definitely an important tip to keep in mind when temperatures drop below what we're used to, one of the main things you may struggle with during those extremely cold times is whether or not you should be dripping your faucets when the temperature dips below freezing. Of course, it's recommended that we drip our faucets as temperatures drop, but the real question is do we actually have to?

Yes, You Should Drip Your Faucet in Cold Weather

According to the Red Cross, the short answer to that question is yes, you do. It's constantly recommended that we drip our faucets in cold weather for one important reason: to prevent our pipes from freezing. "When the weather is very cold outside, let the cold water drip from the faucet served by exposed pipes. Running water through the pipe—even at a trickle—helps prevent pipes from freezing." And while that may cause concern for those of you who like to keep your water bills low each month, letting your faucet drip may save you a bigger bill for repairing your pipes.

At What Temperature Do Pipes Freeze and Burst?

So what do "below temperature" numbers look like? Farm Bureau Insurance noted that pipes have a temperature alert threshold of 20°F—which means pipes will begin to freeze at this temperature and in some cases, even burst. That doesn't mean, however, that pipes will only freeze if the temperature is at 20°F and below. If your pipes happen to be exposed to cold air or are not insulated, the freezing—even if you are dripping your faucets—can still occur at temperatures above the noted threshold.

How to Thaw Frozen Pipes

If by chance you forget to drip your faucet (or just haven't gotten to the point where you're sold on doing so) and your pipes freeze over, know that not all is lost immediately. If your pipes are still in good standing and haven't burst after freezing, State Farm revealed that you may be able to unfreeze them with an appliance that you use daily: your hair dryer. Before heating the pipe closest to the faucet to try your hand and thawing it out, however, you'll want to make sure you're not standing in any water as to avoid any harm to yourself and others.

Overall, it's best that you take heed and drip your faucets when temperatures dip below freezing. A simple trickle of hot and/or cold water—both from faucets inside and outside the home—can prevent you from having to deal with a much larger issue (and bill!) in the long run.

How long should you leave the water running?

After all faucets are open, let the COLD WATER run for at least 30 minutes. During this time, also flush each toilet in your home 2 or 3 times. Running the COLD WATER should remove any old (stagnant) water which may contain higher concentrations of metals including lead, if it exists in your service line or plumbing.

What will happen if we keep the water tap running for a very long time?

This reduces the pH level of the water and gives it an off taste. But even then this water is safe to drink. Moreover, most experts believe that tap water has a shelf life of six months. After this period, the chlorine in the water dissipates to such a point that bacteria and algae start to grow in it.

Should you leave water running so pipes don't freeze?

When the weather is very cold outside, let the cold water drip from the faucet served by exposed pipes. Running water through the pipe - even at a trickle - helps prevent pipes from freezing.

Is it bad to leave faucet running?

Running water through the pipe—even at a trickle—helps prevent pipes from freezing." And while that may cause concern for those of you who like to keep your water bills low each month, letting your faucet drip may save you a bigger bill for repairing your pipes.