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Why Are Pipes Sweating? (Explained)

Sweating pipes are all too common in the plumbing world. Under the right circumstances, even the coldest pipes can start to sweat. Why is this happening, and what can you do to prevent it? Let’s look at the causes and solutions of sweating pipes.

Why are pipes sweating?

A temperature difference between the inside and outside of a pipe causes it to sweat. A liquid that evaporates from a warmer liquid can form sweat on piping parts. Moreover, pipes may sweat due to blockages, foulness or buildup, or moisture condensation.

Sweating occurs when something, such as dirt or grease, has formed inside the pipe and is preventing water from flowing freely. This will cause the liquid in the pipes to heat up, causing the pipe to sweat as well. Pipes can sweat for several reasons, including:

Temperature differences in the pipe and outside:

The first cause of pipe sweating is temperature differences between the inside and outside of the pipes.

There will be a greater temperature differential between the two when it’s cold outside. Liquid can evaporate from colder liquids and parts of the piping system can sweat.


Dirt or grease can also cause pipes to sweat when they form in areas where water should flow freely. Consequently, heat builds up in the area where water shouldn’t be, causing you to sweat.

Foulness or build-up in pipes:

A buildup of foulness or other contaminants inside the pipes can also cause pipes to sweat.

This can cause sweating on parts of the piping system because liquid cannot evaporate. When contaminants are present inside pipes, sweating almost always occurs.

Moisture condensation on the outside of pipes:

Moisture condensation on the outside of pipes can also cause pipes to sweat.

Water vaporizes more quickly on the cooler side when it’s cold outside and the temperature differential is large between inside and outside. Sweating occurs when moisture condenses on surfaces like metal pipes.

Sweating from a burst water pipe:

A burst water pipe can also cause sweating. High pressure and sudden temperature changes can cause pipes to sweat.

Most often, this occurs in older homes where pipes are made from different materials than today’s plastic PVC piping. Moreover, sweating pipes can indicate a more serious water main break.

Are pipes supposed to sweat?

Pipes are usually not supposed to sweat. Several factors can cause sweating, and it is usually a sign that something is wrong with the piping system. Here are some pipes and the possibility of them sweating.


HVAC pipes:

Pipes in HVAC systems are sometimes prone to sweating. In most cases, it does not pose a serious problem.

Additionally, sweat will not cause a pipe to burst. Nevertheless, if sweating is excessive, it may indicate a problem and needs to be addressed immediately.

Well water pipes:

Normally, water pipes in wells aren’t supposed to sweat. Sweating over time can cause damage to the pipes and cause a leak to develop.

It may, however, be an indication that something is wrong with the pipes if sweating is excessive or if there is repeated leaking of water.

Central air pipes:

The pipes in the central air system are not supposed to sweat. In most cases, central air pipes are made of plastic and PVC, which are materials that do not usually sweat.

When sweating is excessive or persistent, it may be an indication that there is a problem with the pipes.


PVC pipes:

In general, PVC pipes do not sweat all the time, but they can sweat from time to time.

Because PVC pipes are made up of plastic, when they sweat, the plastic will heat up and can cause a burst because of the heat. Water pressure or temperature spikes usually cause PVC pipes to sweat

Copper pipes:

A copper pipe would normally not sweat, but if sweating is excessive or persistent, it may be a sign that there is a problem with the pipes that need to be addressed.

Most of the time, sweating won’t cause a pipe to burst.

What to do if pipes are sweating?

The first thing that you need to do if you see your pipes sweating is to identify what the problem is and then seek a solution.

If sweating is caused by high water pressure or temperature spikes, then you should take the necessary measures to avoid sweating in the future.

Experiencing excessive sweating or water leaks regularly may indicate a problem with your pipes. Consequently, it may be necessary to replace the pipes if there is a problem with them.

However, in most cases, the warm, moist air causes pipes to sweat because it is so humid.

Typically, if this happens, two things need to be fixed: the sweating pipes themselves and the cooling system of the building in which the sweating pipes are located.

Water valves that are causing the sweating pipes can usually be tightened up or anti-sweat surfaces can be installed on them.

However, the cooling system may require a bigger repair, such as replacing whole sections of pipes or replacing the central air conditioning system.

In addition, sweating pipes can be a sign that there is something wrong with the plumbing system in your house. If you are noticing sweating pipes, it is always best to contact a professional plumber for further inspection.

How to fix sweating pipes?

Fixing the causes of excessive sweating is the easiest way to fix sweating pipes. It may be necessary to adjust water valves, install anti-sweat surfaces on pipes, or replace sections of piping. To fix sweating pipes, follow these guidelines:

Identify the causes:

It is most likely that sweating pipes are caused by warm moist air. Check the cooling system of your building for broken orifice seals, failed evaporators, or leaks to determine where the excess moisture is coming from.

It may be necessary to look closer at the pipes and fittings themselves if these are not the problem.

Fix faulty piping:

Fixing high water pressure or temperature spikes will usually reduce sweating significantly if sweating is caused by these factors.

Occasionally, however, it may be necessary to replace the pipes completely. Make sure there are no obvious problems with your building’s water pressure and temperature.

Install pipe insulation material:

A pipe insulation material can help to reduce sweating by trapping warm air and preventing it from coming into contact with the pipes, which can lead to sweat.

Pipe insulation reduces sweating by trapping warm air and preventing it from contacting the pipes, which can cause sweating

Dehumidify with AC:

In most cases, air conditioning units are effective at reducing sweating.

In homes without AC units, you can try other dehumidifying methods, such as using a de-icing fluid on the outside of pipes or installing desiccant cabinets in the room where the pipes are sweating.

Check for water leaks:

Another common cause of sweating pipes is leaking. You can check for leaks by measuring the height and volume of water used in your building each day with a meter. Additionally, look for puddles or wet spots where the piping meets the floor or walls.

How do you prevent condensation on pipes?

There is always a better option to prevent the problem from occurring before it becomes a problem. To prevent moisture from condensing on pipes, there are a few things that you can do to try to prevent it from happening in the first place:

Use insulation material:

By trapping warm air and preventing it from coming into contact with pipes, pipe insulation material can reduce sweating because it prevents warm air from coming into direct contact with them.

Insulation for pipes can be found in a variety of materials, such as foam, fiberglass, and plastic, among others.

Additionally, if you are using plastic pipes, you should make sure they are properly sealed so that moisture cannot get in and cause sweating if you use them.

Install de-humidifying equipment:

One of the most effective methods of reducing sweating on pipes is air conditioning. Alternatively, you can use dehumidifying methods that do not require air conditioning.

You can use de-icing fluid on the outside of the pipes or install desiccant cabinets in the rooms where the pipes sweat if you do not have an air conditioner.

Equip water repellent coating:

Another preventative measure that you can take is to coat your pipes with a water-repellent coating so that they can resist moisture.

In this way, the amount of moisture that ends up on the pipes and causes sweating problems will be reduced as a result of this.

Ventilate the area well:

Additionally, it is very important to ventilate the area well to avoid moisture from condensing on the pipes as well.

To reduce the amount of water in the air, it is recommended that you open windows, install fans, and use air conditioning if necessary.

You can also use a humidifier. However, it is important to note that these measures may not be sufficient if you are sweating pipes in a humid environment.

Install a watertight capping system:

You could also try installing a water-tight capping system on sweating pipes if all other measures prove ineffective. It will prevent condensation and moisture from building up on the skin and cause sweating problems if this is done.

Final thoughts

Temperature variations, blockages, foulness or build-up in pipes, and moisture condensation can cause pipes to sweat. To fix insulate pipes with thermal insulation. Dehumidifiers remove moisture from the air. Reduce moisture on contact by coating pipes with a water-repellent coating.