You empty the water tank of a dehumidifier as soon as it is full. How often that is depends on the tank capacity and how much moisture the device removes from the air. With a 3.8-liter tank and a maximum output of 900 ml per day, the tank is full after just over four days. In a drier house it takes longer, in a very damp room it fills up faster.
Direct answer: empty the water tank of a dehumidifier when it is full; in very damp conditions this may be daily, in an average situation often once every few days.
What determines how quickly the tank fills up?
The tank fills with the moisture that the dehumidifier removes from the air. How much that is depends on the humidity in the room, the temperature, the size of the room and how long the device is switched on. The stated capacity, such as 900 ml per day, is a maximum under favourable conditions. In practice, a device in a room that is already fairly dry will remove much less water from the air.
If you use the dehumidifier in a room where clothes are hanging to dry, the tank will fill up faster than in a bedroom. Also read how to dry clothes faster with a dehumidifier: in such a situation you will need to empty the tank more often.
A calculation example with the Dynter DH251
The DH251 has a 3800 ml water tank and removes up to 900 ml of moisture per day. At maximum output, you divide 3800 by 900: just over 4.2 days. If the device removes only half that on average from the air, so 450 ml per day, it will take just over 8 days. These are calculation examples; the actual output depends on your situation. The device also has a safety sensor that switches it off when the tank is full, so that nothing overflows.
Is the device in a room that you do not visit often, such as an attic or basement? Then you can choose to empty the tank a little earlier, so that the dehumidifier does not unnecessarily stop. In a basement, a full tank is a common reason for moisture to return; read about this in how a dehumidifier helps in a damp basement.
What do you do with the collected water?
The water from a dehumidifier is condensation water. It is not intended for drinking. For certain purposes, such as an iron or cleaning, it can be used; read about this in how you can reuse the water from a dehumidifier. Otherwise, simply pour it down the sink or toilet.
Do not leave the water in a nearly full tank for days. Standing water can start to smell. Rinse the tank when emptying it and let it dry thoroughly occasionally. More maintenance tips can be found in our article on how to clean and keep a dehumidifier fresh.
Emptying the tank is not a solution to a moisture problem
Always having a full tank may mean that there is an underlying cause. According to Milieu Centraal, mould is a sign of moisture problems and insufficient fresh air, and recurring moisture problems often stem from an underlying cause such as a leak, rising damp or limited ventilation options. According to Milieu Centraal on ventilating homes, dehumidifiers and moisture absorbers do not solve the moisture problem and do not replace ventilation. A dehumidifier is therefore a tool, not a repair. If you have complaints that you attribute to moisture or mould, discuss them with your GP.
How long you need the device for per day also depends on the situation. Read about this in how long a dehumidifier needs to be switched on per day.
Dynter DH251 dehumidifier
Product: Dynter AirPure DH251 dehumidifier
Capacity: up to 900 ml per day
Water tank: 3800 ml, with safety sensor that switches off when the tank is full
Room: suitable for rooms up to 55 m²
Consumption: 80W, weight 2.51 kg
Extra: timer function from 1 to 24 hours and a night mode where the display turns off
The Dynter DH251 dehumidifier has a large tank, so you do not need to empty it every day. More options can be found in the dehumidifier collection.
Overview: how long does it take before the tank is full?
| Output per day (example) | Tank capacity | Tank full after approx. |
|---|---|---|
| 900 ml (maximum DH251) | 3800 ml | 4.2 days |
| 450 ml | 3800 ml | 8.4 days |
| 300 ml | 3800 ml | 12.7 days |
Frequently asked questions
What happens when the tank is full?
With the DH251, a safety sensor switches off the device when the tank is full. Empty the tank and put it back to continue.
Can I pour the water down the sink?
Yes. It is condensation water and not intended for drinking. You can simply pour it down the sink or toilet.
Do I need to empty the tank every day?
Not necessarily. With a 3.8-liter tank and a maximum of 900 ml per day, it takes just over four days. In a very damp room, it may be necessary to empty it more often.
Why is my tank filling up faster than expected?
This means that there is a lot of moisture in the room, for example due to laundry, cooking or an underlying moisture problem. Also look at ventilation and the cause of the moisture.