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Does an Air Conditioner Use Water?


Air conditioners have become indispensable to modern life, a revolutionary invention, as one might say. It provides respite from scorching summers and creates comfortable indoor environments. After years of using ACs, have you ever asked yourself, does an air conditioner use water?

In this post, we will delve into the inner workings of AC units to understand if and how water is involved in the cooling process.

How Air Conditioners Work

Does Air Conditioner Use Water?

Before exploring the water-related aspects, it’s essential to have a basic understanding of how an air conditioner works. Air conditioning units operate on the principles of thermodynamics, specifically the process of refrigeration. The primary components of an air conditioner system include a compressor, condenser, expansion valve, and evaporator.

  1. Compression: The process starts with the compressor compressing a low-pressure, low-temperature refrigerant gas into a high-pressure, high-temperature gas.
  2. Condensation: The hot refrigerant gas then moves to the condenser coils, releasing a warm draft and condensing into a high-pressure liquid.
  3. Expansion: The high-pressure liquid refrigerant passes through an expansion valve, causing it to expand rapidly, leading to a drop in pressure and temperature.
  4. Evaporation: The cold refrigerant moves to the evaporator coil. Here, it absorbs hot air, which cools the air down and turns the refrigerant into a low-pressure gas.
  5. Recycling: The cycle repeats as the gas is drawn back into the compressor to restart the process.

Do air conditioners produce water? Yes, it happens because of the condensation process, converting water vapor in the air into liquid water, commonly referred to as condensate water. Condensate water occurs when warm air contacts cold surfaces below the dew point temperature, thus producing those water droplets.

Does an Air Conditioner Use Water?

Water cooled AC

Now that we understand the basic process of how air conditioners work, let’s address whether they use water in this process. The answer is that it depends on the type of air conditioner. 

There are two primary categories of ACs: air-based and water-based ACs. Most ACs, commonly found in homes and buildings, fall under the air-based category. These systems do not utilize water for cool air. Instead, they employ a refrigerant gas or ‘freon’ that follows a cycle of compression and expansion. This cycle enables warmth removal from indoor air, subsequently releasing it outside.

In contrast, water-based ACs incorporate water as a central component of their cooling mechanism. These systems use water as a medium to facilitate the cooling process. It’s essential to recognize that not all ACs involve water, and it primarily applies to the water-based AC variant.

What Is the Difference Between Water and Air-Based AC?

When choosing an air conditioner unit, it’s crucial to consider the type of cooling system that best suits your needs. Two popular options are air and water-cooled ACs. Let’s compare these systems based on key factors:

Cooling Mechanism

  • Water-based: Water-cooled units use water. It absorbs the warmth from the indoor air, which then circulates through a water-cooling system before releasing a hot breeze to the outside environment.
  • Air-based: Air-based units rely on air as the cooling medium. It transfers the warm draft from the indoor air to the refrigerant, then is pumped through condenser coils, releasing the warm breeze into the outdoor air.


  • Water-based: Generally more energy-efficient and effective in large-scale commercial applications. It maintains a stable temperature, regardless of outdoor conditions, making it suitable for consistent and heavy-duty cooling requirements.
  • Air-based: Typically less energy-efficient compared to water-cooled units. They are commonly used as residential air conditioners, providing cooling based on the surrounding air temperature.

Space Requirements

  • Water-based: Requires additional space for water-cooling towers or cooling ponds, making it more suitable for areas with ample outdoor space, like commercial units. 
  • Air-based: Compact and space-efficient. It does not require external water sources, making it easier to install in various locations, including urban environments. It’s suitable for small spaces.


  • Water-based: Requires more maintenance of its water-cooling systems, including filtration and water treatment, to prevent scaling and bacteria growth.
  • Air-based: Generally easier to maintain with routine cleaning of air filters and condenser coils.

Noise Level

  • Water-based: Tends to be quieter than air-cooled units due to the water-cooling procedure.
  • Air-based: This may produce more noise, particularly in outdoor units, due to the operation of fans.

Environmental Impact

  • Water-based: May use significant amounts of water, raising environmental concerns in areas with drinking water scarcity.
  • Air-based: Generally considered more environmentally friendly as it does not consume large amounts of water.

Choosing between air-based and water-cooled AC units depends on efficiency, space requirements, maintenance, and environmental impact. The water-cooled air conditioner is more suitable in large buildings as commercial air conditioners, while air-based units are commonly used in residential homes as residential air conditioners.

What Kind of Air Conditioning System Use Water as its Coolant?

Now that we understand how air conditioners work and the difference between water-cooled and air-cooled AC units, let’s address what kind of AC units use water and how they use it in this process.

Typically, residential air conditioners (split units, window units, and portable air conditioners) do not use water to refresh the air. These residential air conditioners chill the air by removing the warm draft and moisture from the indoor environment through the air filter, and the condensed moisture is usually drained outside through a large tube or collected in a drip pan. 

Now, there are four types of water-based AC: 

Evaporative Cooler (Swamp Cooler) 

An evaporative cooler uses water to refresh outdoor air through evaporation. Warm, dry outdoor air is drawn through water-saturated pads. As the air passes through the wet pads, the water becomes water vapor, absorbing warmth from the air and cooling it down. 

The cooled air is then circulated indoors. Evaporative coolers are most effective in dry and arid climates where low humidity allows for efficient evaporation. They are usually an outdoor unit type of AC that evaporates the warm draft inside below the dew point temperature. 

Water-Cooled Package Unit

A water-cooled package AC unit is a self-contained air conditioning system that incorporates cooling components within a single package. These units typically include the compressor, condenser, evaporator coils, and a water-cooled condenser. Water removes warmth from the condenser coils, and a water pump circulates the water to aid in warmth dissipation. These units are used when air-cooled systems are not efficient enough due to extremely hot air loads.

Water-Cooled VRF System (Variable Refrigerant Flow)

A water-cooled VRF system is a type of air conditioning system that uses a water-cooled condenser in conjunction with a variable refrigerant flow system. The system uses freons to transfer heat between indoor and outdoor units, and water is used to freeze the freon in the condenser coils. These systems provide efficient and flexible cooling solutions for large commercial buildings.

Chilled Water System

A chilled water system is a central cooling system used in commercial and industrial buildings. It utilizes chilled water as a heat transfer medium to cool indoor spaces. The cold water produced is circulated through pipes to air handlers, which absorb heat from the air. The warmed water is then sent into cooling outdoor unit towers where heat is evaporated. The water produced now returns to the system to repeat the process.

Water plays a crucial role in all these systems, but how it is used differs:

  • Evaporative Cooler: Water becomes water vapor to cool outdoor air, providing evaporative cooling.
  • Water-Cooled Package Unit: Water cools the condenser coils in a closed-loop configuration, where the water absorbs heat through evaporator coils and is pumped to a cooling tower for cooling.
  • Water-Cooled VRF System: Water is used to cool freon in the condenser coils, enhancing the efficiency of the heat exchange process.
  • Chilled Water System: This system absorbs heat from indoor spaces and is cooled through evaporation in a cooling tower.

The choice between these systems depends on climate, cooling requirements, efficiency goals, and the specific demands of the cooled building or space.

How Much Water Does an Air Conditioner Use?

The amount of water an air conditioner uses can vary widely depending on several factors, including the type of air conditioner, its cooling capacity, operating conditions, and climate. 

Every HVAC system possesses distinct water consumption, regardless of its classification as a water-based AC. Here are some general guidelines:

Air-Cooled Air Conditioners

Most residential and commercial air conditioners have a closed-loop freon system and do not consume water regularly. These systems rely on the refrigerant cycle to transfer heat without water involvement. As a result, they don’t consume water for cooling purposes.

Evaporative Coolers

These systems can consume significant water, especially in arid climates with high evaporation rates. The exact water usage will depend on factors such as the size of the cooler, humidity levels, and the desired indoor temperature. 

A portable device could consume around 4 liters of water in an hour, while a centralized system might utilize up to 25 liters within the same timeframe.

Water-Cooled Air Conditioners 

The water consumption of water-cooled package units and VRF systems is contingent on their capacity and the cooling load they are designed to manage. 

About 1.8 gallons of water evaporation are necessary for each tower ton (equivalent to 15,000 BTU/hr), equal to roughly 0.03 gallons per minute per ton.

Chilled Water System

Chilled water systems function as entirely enclosed circuits. Thus, it consumes no water when functioning correctly and without any water leaks. However, if cooling towers facilitate the refrigeration cycle, each ton of cooling necessitates approximately 2.0 gallons of water evaporation per hour for the tower’s operation.

If you’re concerned about water usage, it’s a good idea to check the specific type of air conditioning system you are considering and consult manufacturers or experts to get accurate information about water consumption.

How Do Air Conditioners Drain Their Water?

While not every aircon employs water in its process, all aircon units generate water as a byproduct. As aircon cools the air, they eventually reach the dew point, forming water byproducts. The following are the typical processes through which they drain this water:

  1. Traditional indoor unit: The collected water is drained outside through a drain pipe or in a smaller tube for split and window units. 
  2. Portable AC: Here, it is passed through a smaller tube and collected in a reservoir or tank. This condensate water is collected on the evaporator coils and then directed to a drain pipe, drain line, pan, or tray beneath the coils.
  3. Water-cooled AC: This type of AC drains water by collecting condensation on evaporator coils. The water flows into a sloped drain pan or tray through a drain line. Gravity guides the water to an external drainage area or plumbing system. If needed, a pump assists with drainage when the unit is located lower than the drainage point.

It’s important to ensure that the drainage system is functioning correctly to prevent leaks, which can lead to potential damage to the AC system. Regularly check your indoor unit ACs drain line.

Ensure your AC does not leak water, as it may cause problems in the copper tubing, condensate line, drain pipe, and more. Also, note that the water produced by an AC is not drinkable.

Regular maintenance and periodic drainage system inspection are necessary to ensure the proper functioning of water-cooled ACs and optimize their cooling performance.

Final Thoughts

Most air conditioners use the principles of refrigeration and do not use water as part of their cooling process. On the other hand, evaporative coolers rely on water’s evaporation for cool air. While portable ACs do not use water for cooling, they generate water as a byproduct, which needs to be managed through drainage or collection.

Knowing the type of air conditioner you have can help you understand its mechanism better and ensure proper maintenance. Regardless of the type, air conditioners have revolutionized modern living by providing a comfortable escape from the sweltering sun, making life more enjoyable during the year’s hottest months.

JP Reyes

JP has been in the aircon industry for almost as long as he has been alive. As a child JP would help his tatay fix aircon units at their junk shop in Cavite. After graduating UP in the early 2000's, JP then started his own Aircon servicing business and within 5 years had 10 shops in 8 different cities. Fast forward to today and JP brings all his experience and expertise online to give readers trustworthy advice and reviews about Air-conditioning buying, servicing, cleaning and repair in the Philippines.

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