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Does Pipe Insulation Absorb Water?

Does Pipe Insulation Absorb Water?

Water pipe insulations bring efficiency to your piping system and delays damage in the long run. Plus, their sound dampening feature also blocks preventable noise from bothering people at home or the workplace. But does pipe insulation absorb water? 

Fiberglass pipe insulation does absorb water, which, unfortunately, reduces the insulating capacity and puts pipes at risk for corrosion. Rubber pipe insulation, however, is water-resistant and a better choice in locations prone to moisture issues.

The succeeding sections will further elaborate on what pipe insulations are, how they can be helpful in household and workplace settings, and the adverse effects of poorly waterproofed insulations.

What Type of Pipe Insulation Absorbs Water?

Fiberglass pipe insulation absorbs water, and some types of plastic and rubber insulations tube will allow water to pass through and reach your pipes. To avoid this, either be sure to seal the insulation with rubber, waterproof tape, or use sealed rubber tubes.

Fiberglass insulation, such as this Home Intuition Foiled Pipe Insulation (link to Amazon), is excellent for use on pipes that are not in wet areas because it’s highly flexible and can be applied in smaller areas and unusually shaped lines. In addition, the foil back helps to prevent any heat from escaping, which makes your pipes more efficient. 

However, fiberglass does absorb water. So, if you don’t thoroughly seal the linings, it is possible that outside water could get in.

Instead, look for something like this Duda Solar Nitrile Rubber Pipe Insulation (link to Amazon), which is water-resistant thanks to the closed structure of the material. I tend to use insulation like this anywhere I have pipes running that I’m concerned that moisture may accumulate.

What Happens When Pipe Insulations Absorb Water?

Yes, pipe insulations do absorb water. But what happens when they do?

When pipe insulations absorb water, their efficacy in conserving heat rapidly drops. The water-exposed pipes also become at risk for corrosion, leading to even more complex problems in the future, such as broken and damaged pipes.

Waterproofing your insulation material reinforces its resilience to wear and tear and increases longevity, providing longer and better protection to your pipe. 


Corrosion occurs when iron comes in contact with oxygen. The process is known as oxidation, and it manifests physically through rust.

Corrosion makes metals less resilient to environmental factors and will yield much faster than uncorroded metal. This means extreme heating events, intense storms, or sudden temperature changes can easily damage or break them. Before you know it, they are already be broken and leaking.

These devastating effects of corrosion on pipes and their corresponding financial implications make waterproofing pipe insulations a necessity (source).

Reduced Insulation Efficiency

Water absorbent pipe insulations allow water such as rain and melted snow to penetrate the outermost layer of the bare pipe. 

The resulting corrosion weakens the pipe, effectively reducing its capacity to serve as an insulator.

How To Protect Your Pipes From Water

To protect pipes from water, start by wrapping them with a waterproof layer. There may also be gaps between lap and butt joints that need to be filled to ensure water does not penetrate through these conjunction points. Rubber tape is an excellent option.

Reyhoar offers this Aluminum Butyl Rubber Tape (link to Amazon) as a simple waterproofing solution. Designed for use on pipes, metal, roofing, window seals, boats, and RVs, this tape claims to be effective for up to 30 years. Plus, it can be used from -40 to 248°F (4.44 to 120°C), so it’s perfect for both freezing and extremely warm environments. 

Another waterproofing option would be Gorilla’s Waterproof Patch and Seal Tape (link to Amazon). Besides being thick and waterproof, it is also UV-resistant. offers the product for less than $15, and it can even be applied underwater.  

What Are the Different Uses of Pipe Insulations?

The different uses of pipe insulations include conserving heat energy, preventing condensation, and reducing sound leakage. Since it keeps outside pipe temperatures within a tolerable range, it also protects workers from burns.

Conserving Heat Energy

At first, it may seem like pipe insulations are additional costs you could easily dodge without any consequences. In reality, however, they are great investments, and you’ll quickly see the perks of having one installed, both in the short and long term.

Insulated pipes conserve heat and effectively deliver up to 4 °F (-15.55 °C) warmer water than bare ones. An insulating material is strategically wrapped around exposed pipes, preventing heat from escaping during operation (source).

Reaching your desired heating temperature requires less energy, so you need not set your water heater to the maximum temperature. This means huge savings on electricity, both in households and work settings. 

Avoiding Condensation

Imagine pouring cold water into a glass on a warm, humid day. You will almost instantly notice droplets forming around the glass surface. A 2-step process facilitates this.

First, the cold water brings the temperature of the glass down. Second, the warm air surrounding the glass comes in contact with its surface. When this happens, condensation occurs. 

Something very similar happens to pipes. 

The water inside the pipes is relatively cold, and they bring the pipes’ temperature down. When the somewhat warmer air comes in contact with the cooler line, water begins to form around it, leading to droplets accumulating on its surface (source).

With pipe insulations, the wrapped insulating material keeps heat from penetrating the pipe, blocking the contact of warm and cold air and effectively preventing condensation.

This can save you the hassle of having to mop the floor when exposed pipes start sweating profusely on humid and warm summer days.

Reducing Noise

Many of us need warm showers to begin a long day or to recover from one. What we don’t need, though, is the loud noise from water passing through the pipes before it gets to our showerheads.

When pressure pumps water into the pipes, it is normal to notice loud noises as a result. 

However, this could also mean that you’ll always have to expect some noise of sorts whenever someone opens the faucet or goes to get a shower. The noise is not only annoying but could also cause serious work distractions.

Pipe insulations can dampen the resulting sound and bring it down to tolerable or even unnoticeable levels (source).  

While they may cost you money initially, the productivity losses from pipe noise could cost you more, so pipe insulations could be a worthy investment.

Providing Personal Protection

Hot pipes can be a work hazard. They can result in burns and other injuries triggered by coming in contact with pipes whose temperature is beyond tolerable levels.

In the workplace context, the U.S. Occupational Health and Safety Administration (OHSA) has set a limit of 140 °F (60 °C) to pipe temperatures. Therefore, if pipes exceed 140 °F (60 °C), a thermal insulator is already required (source).

According to OHSA, more than five seconds of physical contact with pipes that exceed the temperature limit can lead to blisters and will qualify as a reportable injury.

Hence, choosing the right pipe insulations does not only protect your business from the added costs of energy inefficient setups. It also aids you in complying with set regulations and minimizes penalties and possible medical expenses from injuries.


Insulating your pipes improves heat transfer efficiency and reduces sound vibrations. It also enhances worker safety, as the insulation protects them from incurring burns. The insulating material also minimizes the possibility of water droplets accumulating around the pipe’s outer surface.

Note, however, that pipe insulation can absorb water. When this happens, the ability of the material to conserve heat or dampen vibrations significantly deteriorates. 

To avoid water leaking into your pipes, pipe insulation must be wrapped with waterproof material. Additionally, fill the gaps between lap and butt joints as these are convenient ways for water to reach the insulation.

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