Basement dehumidifier cost
A basement dehumidifier costs $200 to $500 portable or $1,500 to $3,500 installed. It is the right answer to a musty basement with no visible water, and the wrong answer to water on the floor.
National average
$500
per each
A basement dehumidifier costs $200 to $500 for a portable unit and $1,500 to $3,500 for a whole-basement unit installed with a drain. Running one costs $10 to $40 a month.
It is the correct answer to a musty basement with no visible water, and it is the wrong answer to a basement with water on the floor. Getting that distinction right saves either a lot of money or a lot of disappointment.
What it costs
| Option | Typical cost |
|---|---|
| Portable unit, 30 to 50 pint | $180 to $350 |
| Portable unit, 50 to 70 pint | $250 to $500 |
| Portable with a built-in pump | $300 to $600 |
| Whole-basement unit, installed | $1,500 to $3,500 |
| Crawl space unit, installed | $1,500 to $3,500 |
| Ducted into the HVAC | $2,000 to $5,000 |
| Condensate pump | $80 to $300 |
| Drain line to a sump or a floor drain | $100 to $500 |
| Dedicated outlet | $150 to $450 |
| Hygrometer | $10 to $40 |
| Running cost, per month | $10 to $40 |
The number to aim for
30 to 50% relative humidity is the target. Below 30% is unnecessarily dry; above 60% is where mould, dust mites and that smell begin.
A $10 hygrometer left in the basement for a week answers whether you have a problem. A lot of people buy a dehumidifier without knowing the reading, and a lot of basements sit at 55% and are fine.
If the reading is above 60%, a dehumidifier is the direct fix. If there is standing water, or damp at the wall-floor joint, that is a water problem and no amount of dehumidification addresses it.
Sizing, and the pint rating
Dehumidifiers are rated in pints of water removed per day. The ratings were revised in 2019 to a lower test temperature, so a modern 50 pint unit is roughly equivalent to an older 70 pint one. Comparing across the change confuses people constantly.
Rough guide for a basement:
| Basement size and condition | Capacity |
|---|---|
| Up to 1,000 sq ft, slightly damp | 30 to 40 pint |
| Up to 1,500 sq ft, damp | 40 to 50 pint |
| 1,500 to 2,500 sq ft, damp | 50 to 70 pint |
| Any size, wet or musty | 70 pint or whole-basement unit |
Low temperature operation matters in a basement. Standard units frost up below about 65°F and stop working. Units rated for low ambient temperature, or with automatic defrost, are what a cold basement needs, and it is a specification worth checking.
Drain it, do not empty it
A portable dehumidifier with a bucket is a device that runs until the bucket is full and then stops. In a basement that is genuinely damp, that is once or twice a day, and the day nobody empties it is the day it does nothing.
Options, in order:
- Gravity drain to a floor drain or a sump, using the hose port every unit has. Free and reliable, if there is somewhere lower to drain to.
- A built-in condensate pump, which lifts the water to a sink or out through a wall. Worth the $50 to $150 extra.
- An external condensate pump, $80 to $300.
Set it and forget it is the entire value proposition. A unit you have to empty is a unit that gets unplugged in March.
Whole-basement units
A dedicated whole-basement dehumidifier is a fixed appliance, ducted or free-standing, with a permanent drain and often a humidistat. $1,500 to $3,500 installed.
Worth it when the basement is finished, when a portable cannot keep up, when the space is large, or when it is a crawl space that has been encapsulated and needs humidity control as part of the system.
They also last longer, run more efficiently per pint removed, and are quieter than a portable working at full output continuously.
Frequently asked questions
Will a dehumidifier fix a wet basement?
No. It handles humidity, not liquid water. If water arrives on the floor after rain, the fix is outside: downspouts, grading, and then drainage. Running a dehumidifier against an active leak is expensive and futile.
Does it help with mould?
Keeping humidity under 60% prevents new mould growth, which is most of the battle. Existing mould needs removing; the dehumidifier stops it coming back.
How much does it cost to run?
A 50 pint unit running half the time draws roughly 250 to 500 watts, which is $10 to $40 a month depending on rate and runtime. Modern units are much better than ten-year-old ones.
Should it run in winter?
Usually not in a cold climate; cold air holds little moisture and basements dry out. Run it from late spring to early autumn and switch it off, which also extends its life.
Where should it sit?
Central, off the floor if possible, with clearance around the intake and exhaust, and near the drain. Not in a corner against a wall, which is where most people put them.
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