How Much Water Should a Dehumidifier Collect in a Day?

In general, the amount of water a dehumidifier collects in a day depends on its rated capacity. Official organizations typically measure this in pints for full-size dehumidifiers or in liquid ounces for mini dehumidifiers. The most common dehumidifiers today range from 20 to 50 pints in capacity. 

On average, small household dehumidifiers can collect about a gallon or two (8 to 16 pints) of water, while the largest can collect up to six gallons (or about 50 pints). However, the actual amount of water your dehumidifier will collect in a day depends on many other factors such as the room size, the air temperature, and humidity levels.

How Much Water Should a Dehumidifier Collect in a Day?

Relative humidity is the amount of water vapor in the air compared to the maximum amount it can hold. The ideal humidity for us is around 30% to 50%. Any less or more will be uncomfortable and also cause a variety of other problems. The main purpose of a dehumidifier is to extract water vapor in the air and collect it in a reservoir, helping you maintain optimal humidity in your home. 

The total amount of this water varies greatly from unit to unit. To understand this, the following are the main factors that impact the amount of water your dehumidifier collects per day.

Dehumidifier Capacity

This is the amount of moisture the dehumidifier removes in 24 hours as measured through tests set by the Department of Energy. The standard dehumidifier capacities today are 20, 30, and 50 pints (or 22, 35, and 50 pints depending on the brand).This is not to be confused with the dehumidifier’s tank capacity.

A higher dehumidifier capacity rating means the unit has greater power to remove excess moisture at a faster rate. This capacity must be the first thing you look for in a dehumidifier. Obviously, a larger dehumidifier will be able to collect more water in a day.

Relative Humidity 

Higher relative humidity means there is more water vapor in the air. Thus, your dehumidifier can collect more water in a high humidity area. A damper or more humid space will require a higher dehumidifier capacity to maintain optimal humidity levels between 30% and 50% RH. If you use the room for household activities like cooking and drying laundry, or even showering, then it will contribute to higher moisture levels and more water collected.

Air Temperature

The relative humidity also affects how we perceive the air temperature. An increase in air temperature means the air can hold more water molecules. So when it’s particularly hot outside, chances are the humidity rises indoors. High relative humidity means the air is saturated with moisture. This is why dehumidifiers are most effective in warm and humid conditions. You can expect your dehumidifier will collect more water during a summer day than any winter day. In fact, most compressor dehumidifiers may not even work in cold climates or below 41°F. 

Room Size

The room size is usually measured in square feet (length x width of the room) or cubic feet (length x width x height of the room). Running your dehumidifier in a larger room means it will have to cover more ground and process a greater amount of air that contains moisture. Using the same dehumidifier in two rooms with similar humidity levels, one room 1,000 square feet larger than the other, the dehumidifier will likely collect more water in the larger room after a certain amount of time.

The dehumidifier capacity rating also determines the room size the unit is suitable for. Energy Star has a size guide for room size and the corresponding dehumidifier capacity, although there are still other factors that may impact the total amount of water a dehumidifier collects.

How Does a Dehumidifier Collect Water?

A dehumidifier collects water using different methods. The two main types of dehumidifiers are called compressor and desiccant. The more common compressor dehumidifier works similarly to an air conditioner. It uses a compressor to circulate refrigerant through the cooling system. Warm, moist air is drawn by a fan then passes through cold coils where the vapor condenses into water droplets. This is what your dehumidifier collects in its water tank. 

On the other hand, a desiccant dehumidifier uses a chemical that binds with the moisture in the air it comes into contact with until the desiccant’s maximum capacity is reached. Most desiccant dehumidifiers don’t have a tank that collects water. If the desiccant is renewable, such as silica gel, it is simply reheated to dry out the moisture.

How Long Does It Take For A Dehumidifier To Work?

There is no one answer to this question. A dehumidifier will start working to remove excess moisture as soon as it is plugged in and turned on. However, you’ll notice varying degrees of effectiveness depending mainly on the dehumidifier capacity, room size, and relative humidity. When used for the first time, a dehumidifier can take about six to 12 hours before you notice a significant change in humidity. In some cases, it can take 24 hours up to a few days of continuous use depending on the scale the dehumidifier is operating. 

Why Did My Dehumidifier Stop Collecting Water?

If your dehumidifier is turned on but the water collection container is still empty after a significant amount of time, there can be a number of reasons for this that may not be an immediate cause for alarm.

Not Enough Moisture

First, the reason may just be that there is not enough moisture in the air to collect. Check the humidity levels in the room and compare it with the humidity setting in your unit. Usually, there should be a 5% to 10% difference or the unit will not dehumidify the room. Remember to maintain humidity levels between 30% to 50% at all times. 

Low Temperature

Another factor that can affect the humidity level is the air temperature. If the air is too cold, your dehumidifier will stop and go on defrost mode to prevent moisture to form frost on the coils. In fact, when the temperature is too low, the air may not even contain a lot of moisture to begin with.

Broken Humidistat

If you’ve checked the humidity and temperature on a separate device and your dehumidifier is still not collecting water, then the unit’s humidistat may be broken. This is the component that measures the humidity and signals the unit to start dehumidifying when the room humidity rises above your setting.

Overheated Compressor

If the fault is not on the humidistat, then your dehumidifier’s compressor may be overloaded. There can also be a number of reasons for this. If frost develops on the coils, or there’s a buildup of dust and other impurities, then the compressor can become overheated. 

There are usually error codes displayed on your unit to identify the problem. You can check the unit’s manual or ask the manufacturer for specific information. If the problem isn’t something you can quickly solve, it’s best to get a technician to look at your unit and find a solution.

Why Is My Dehumidifier Filling Up Faster?

The time before you need to empty your water collection tank largely depends on the unit’s capacity and the size of the tank. Portable dehumidifiers have a tank capacity that directly relates to the unit’s moisture extraction rate. A higher dehumidifier capacity comes with a larger tank but the exact amount varies per brand and model. Obviously, smaller tanks will fill up quicker.

If you notice your dehumidifier fill up its tank faster than usual, it can simply be because of sudden changes in temperatures and humidity levels. Furthermore, if the unit is coming from a defrost cycle, the melted ice will drip down into the tank. If any of these isn’t the case, then the problem may be in the unit’s internal components. Likewise, have your unit checked by a professional.


How many times a day should you empty a dehumidifier?

You must empty your dehumidifier tank as soon as it’s full to resume operation and also prevent mold growth inside. Most dehumidifiers will need to be emptied at least once or twice a day depending on room size and conditions. Even if your dehumidifier doesn’t fill up, empty it every day after use.

Should you run a dehumidifier constantly? 

No, you don’t need to keep your dehumidifier running constantly. Turn it on only when humidity levels reach above 50% RH, then turn it off once your target humidity level is achieved. If you need to leave, program the unit to automatically turn off to save energy.

Do you need to run a dehumidifier in the winter?

You should run a dehumidifier only when the air is humid. It’s dry and cold in the winter so you typically won’t need a dehumidifier.

Wrapping Up

Dehumidifiers collect water to maintain ideal humidity levels in your home. The exact amount of moisture each unit collects in a single day can go anywhere from one to six gallons or 10 to 50 pints. It depends on a lot of factors, including the dehumidifier capacity, room size, humidity, and temperature. To make sure your dehumidifier is collecting water efficiently, you must use only the correct size for your room. We have guides to help you accomplish this for different types of spaces in your home.

Related Articles