Blog

Moisture in compressed air: Causes, problems, and how to remove it

If you've ever opened a drain valve and seen water pouring out of your compressed air system, you're not alone. Moisture in compressed air is a common issue—and one that can quietly cause serious damage over time. In this guide, we’ll break down why compressed air contains moisture, what problems it can cause, and—most importantly—how to remove water from your system using the right equipment.

Why is there moisture in compressed air?

The air around us always contains water vapour. When you compress that air, its volume decreases, but the moisture content doesn’t. This increases the air’s relative humidity—and once it hits saturation point, condensation begins to form. The result? Water accumulates inside your compressed air system, especially after the compression and cooling stages.

 

Several factors influence how much moisture forms:

 

 

  • Ambient temperature and humidity
  • Compressor type and size
  • Air flow rate and pressure
  • Cooling stages and aftercoolers

 

Moisture in compressed air

The hidden cost of wet compressed air

Moisture in compressed air can lead to a long list of operational headaches—many of which come with a price tag:

 

  • Corrosion in pipelines, valves, and tanks
  • Premature failure of tools and machinery
  • Inconsistent product quality in food, pharma, and electronics
  • Clogging of filters and nozzles
  • Freezing in outdoor lines during winter
  • Microbial growth in high-moisture environments

 

Even if it’s not visible, excess moisture can quietly reduce system efficiency and increase energy consumption.

Where moisture builds up

Water doesn’t just stay at the compressor. It shows up throughout the compressed air system, especially in:

 

  • Receiver tanks
  • Filters and dryers
  • Distribution piping
  • End-use tools and machines

 

Condensate often collects in low points and corners, which is why proper drainage and air treatment are so important.

How to remove moisture from compressed air

Air dryers
Installing a compressed air dryer is the most effective way to remove water vapour from your system. There are two main types commonly used:

 

  • Refrigerant dryers cool the air to condense and drain moisture. They are ideal for general-purpose applications and typically reach dew points around +3°C.
  • Desiccant dryers use drying agents to absorb moisture from the air, allowing for much lower dew points—down to -40°C or below. These are particularly suited to critical environments or colder climates.

 

Condensate drains
Automated or timed condensate drains are used to remove collected liquid water from tanks, filters, and low points in the system before it can be carried further downstream.

 

Filtration
Although filters don’t remove water vapour, they are essential in capturing water aerosols and other contaminants that may remain after drying—providing a final line of protection for tools and processes.

 

Dew point monitoring
Installing a dew point sensor or meter gives you real-time insight into the air’s dryness. Monitoring dew point ensures your drying equipment is performing as expected and helps prevent moisture-related issues.

Get in touch

Moisture is an inevitable part of compressing air—but it doesn’t have to be a problem. By understanding where water comes from and how to remove it, you can protect your equipment, reduce maintenance costs, and improve overall reliability. Want help finding the right air dryer or moisture control solution? Contact our experts, we’ll guide you to the best fit for your application and operating environment.