Take the 2-minute tour ×
Home Improvement Stack Exchange is a question and answer site for contractors and serious DIYers. It's 100% free, no registration required.

I have a split A/C system in a room that runs on low 24 hours a day during Summer that unfortunately cannot be connected to any drain or pipe and which therefore requires a bucket outside to be used to collect the condensate from the condensate drain line in the exterior unit that sits on my balcony in my apartment building.

This is quite frustrating as the bucket has to be emptied every single day (once a day), so I'm looking for a better solution.

The bucket is already quite large and gets quite heavy at the end of the day when it's full, so maybe something that makes the water evaporate faster than normal so that I don't have to empty the water so often?

Does such a solution exist or am I condemned to a lifetime of emptying the bucket every night during Summer?

** 14 May 2015 EDIT **

I have not yet been able to solve this issue.

Without going into details, connecting the condensation drain line to any drain of any kind, drain line, drainage hole, ground, pumps, pipes, etc. is NOT an option, so I need an outside-the-box solution.

The A/C Condensate Drain Line seems to empty about 3 Gallons / 12 L per 24 hour period.

Potential solutions:


  • Are there outdoor-friendly humidifiers that could get rid of 3 Gallons/ 12 L per day? The tank would not have to hold that much as the drain line would just drip the water constantly into the tank.

  • CONSIDERATIONS: Would I need to use more than 1 humidifier and serialize them? Can a humidifier handle being on for 24 hours a day for 4 months straight? Can a humidifier handle the elements (e.g. could rain affect the circuitry or create any electrical issues)?

Plant/Grass garden

  • My balcony has 37sqft / 3.4 m2 of area to play with but only 1 hour of direct sunlight (although plenty of indirect sunlight) per day, could I create a garden of plants/grass to absorb the water?

  • CONSIDERATIONS: How much garden would I need? Which plants could meet this criteria? Could the balcony handle the weight of soil + plants + water?

NEW: Drip Tray + Humidifier Wick

  • What about something like this plus several of these, could that evaporate 3 Gallons / 12L per day?

  • CONSIDERATION: Would they get clogged from dirty city air? How many wicks would I need to evaporate all that water?

Any other outside-the-box solutions?

Would any of the solutions listed above work? If so, what specific details would I need to make it work? Are there any other solutions?


On the hottest Summer months, the average relative humidity is about 72%, with about 9 mean daily sunshine hours, 1-2 inches of monthly rain, and daily mean temperatures of about 76 F / 24 C (with average highs of 84 F / 29 C). Remember, however, that the balcony only receives about 1 hour of direct sunlight, although plenty of hours of indirect sunlight.

enter image description here

As you can see, it gets VERY dirty due to this being in the inner city next to a large avenue where a lot of cars run through creating a lot of direct air pollution, so any solutions that may clog need to take this into account. This is another reason I want to avoid having to open the balcony doors to empty it every night. In case it helps, the model of the outdoor unit is Mitsubishi MXZ-18TV.

share|improve this question
You can't just let it drain on the ground? –  Tester101 Jul 2 '14 at 17:30
Why can't it be connected to a drain of some sort? And why is it not dripping onto the ground? –  Ghost Jul 2 '14 at 17:42
The two things that will increase evaporation is larger surface area (a pan instead of bucket) and increased air flow. I'm assuming you can't make any modifications to apartment, but you can probably get away with attaching a hose to the drain and letting it go over the side of the balcony. –  diceless Jul 2 '14 at 18:27
Where do you live? A permanently installed air conditioner that doesn't have a proper, permanent drain wouldn't meet code in most US jurisdictions. –  longneck Jul 3 '14 at 1:24
I, too, am confused as to how regulations allow your building to install a mini-split system, but not account for condensation drainage. FYI, most mini-split systems are already deigned to have an exterior drain. This seems like a building management issue. –  DA01 May 14 at 19:11

11 Answers 11

up vote 6 down vote accepted

While you can't have it drip off the balcony, you can turn it into a fine mist and blow it off. Even a fine sprayer would work fine, but you'll need a float switch to auto-activate it, and a pump. On the plus side, this will air condition your balcony as well.

Home Depot has a bucket-top misting fan that looks like it would solve your problem. You would need to hook it up to a battery or adapter.

share|improve this answer
Where could I find a "fine sprayer" that is outdoor-friendly? What's a float switch? Would a pump really be necessary if the A/C is above whatever I put on the balcony (e.g. gravity would push the water)? Please clarify, thank you. –  ProgrammerGirl May 14 at 14:53
Powered mist sprayers are designed to work off of household water pressure (60psi or above) so they are not going to be directly compatible with your situation. If you found one with a storage vessel (i.e. didnt require hooking up to a hose) you could make it work. –  Jeff Meden May 14 at 16:59
See edit. Seems that there are a lot of submersible bilge pumps that would be useful in this scenario –  gbronner May 14 at 17:12
@gbronner: The bucket-top misting fan actually looks like one of the most promising solutions. Is there a version that can be plugged in? How much water/power does it consume per day? –  ProgrammerGirl May 14 at 18:23
Not a ton of power -- 30 watts/hr. Not sure how much water it uses, but evidently enough so that a 5g is necessary. You can get or make an adapter that should work -- this isn't a crazy electrical load. Google AC adapter Ryobi and you'll see a lot. It will also make your deck much more comfortable. –  gbronner May 14 at 19:39

Set up a fan and drip the condensate into the the spinning fan blades. Have the fan blowing the water mist away from the balcony. The optimal fan to do this would be a high RPM high CFM small diameter fan. There are many IP52 water resistant computer case fans that can do this... like this one.

The fan can be powered by something like this.

I would use the existing mounting holes in the case fans and some rope/wire/zip-ties to securely mount the fan under one of the balcony railings. Then tie the condensate drain line to the railing and let it drip down in front of the intake side of the fan, such that the water gets sucked into the fan blades. Let the fan run constantly whenever you use the AC.

Having the fan blowing at the end of the condensate tube would be simpler, but would only work if the air speed from the fan is high enough.

share|improve this answer
I'd guess the A/C unit has a fan on it already, could the condensation be dripped on that fan? –  Tester101 May 14 at 14:45
Interesting solution! So how would I set this up, exactly? Could you possibly do a rough drawing of what this would look like and what I would need to build it and connect it all? Thank you! –  ProgrammerGirl May 14 at 14:55
Cant make a drawing right now but you would need a power supply amzn.com/B000MGG6SC and some ropes/wire to tie the fan to something. –  Netduke May 14 at 15:28
This is exactly how window units work. Alas, rarely can the fan 'mist' the condensation faster than it accumulates. You will still likely have more condensation than the fan can deal with. –  DA01 May 14 at 19:15

If there really is no possibility of connecting it to a drain with its normal gravity flow, your only non-bucket option is to install a condensate pump, whose job is to raise the liquid up to a height where you can easily dump it in a drain or on the lawn or something. These are very common for basement installations of central air conditioning units where the condensate line is below the level of any drain plumbing.

Condensate Pump: (zoro.com) (diychatroom.com)

enter image description here enter image description here

share|improve this answer
Is there access to the rain gutter from the balcony? If so you might be able to run the output from a condensate pump up into the rain gutter. If you're in the US you can get condensate pumps at Lowes or Home Depot or on the net. You'll also need tubing for the output and cable ties for a cleaner look. –  John Dyer Jul 2 '14 at 19:28
This is the most workable solution here. The pump doesn't require modification the the apartment. Just run the output tube from the pump along the wall to a sink. –  longneck Jul 3 '14 at 1:21
@ProgrammerGirl Pipes and hoses are technically different. In theory you could have a hose that would move the water most of the time out of your bucket. There might be some days where the hose is rolled up and the hose/pump system is not used. You can't really do that with a pipe system. –  Dano0430 May 14 at 15:03
@ProgrammerGirl I don't think so. The one's I have for my garden definitely drip. Additionally you cannot control where it drips. A hose though you could run to your sink and have it drain in the sink and roll up the hose if you're not using it. Then you would only have to flip a switch or plug in your pump when needed. Edit: this hose would work great for a garden (See iLikeDirt's Answer) –  Dano0430 May 14 at 16:40
Yes, a hose is not a 'pipe'. It's like running an extension chord. It is in no way considered 'modifying' the structure. And it's not even really a hose. You can pick up fairly inconspicuous small clear drain lines at Home Depot. Easy enough to tuck along the perimeter of a room. –  DA01 May 14 at 21:54

OK, if you can't change it, and they own the A/C, and you previously agreed to the current state of affairs but are now annoyed by it, here's another idea: plant an extremely water-thirsty plant that will transpire a large amount of water every day. Then just water it with the condensate. Grass can have a high transpiration rate. Maybe you could have a little patch of turf on your balcony! Bamboo also transpires a lot and accept very moist soil. There are lots of options.

share|improve this answer
I have added details about the size of the balcony and how much sun it gets. Considering that criteria, which plants/grass would work? –  ProgrammerGirl May 14 at 14:06
Lots of water + 1 hour of sun per day = swamp-adapted plants. Check out aquascapesunlimited.com/index.cfm/fuseaction/plants.main/typeID/… –  iLikeDirt May 14 at 15:39
Is there a way to calculate how many swamp-adapted plants I would need so that I can calculate the weight it will all add to the balcony? –  ProgrammerGirl May 14 at 16:07
Well, it depends. I've read that grass, for example, requires at least 10cm of soil depth to grow. I have about 3.4 m2 to grow stuff on, so 10cm of depth covering 3.4 m2 would be 0.34 m3 of soil, or 340 L. If soil weighs at least as much as water, then that's at least 340 kg (750 lb) of dry soil before I even add the water and plants. So I think it would be important to know how many m3 of soil I would need before I embark on this potential solution. –  ProgrammerGirl May 14 at 17:44
You're entering the land of analysis paralysis. Just pick something and give it a shot, within the bounds of safety and sanity. You can spend your whole life trying to engineer the perfect theoretical solution and never implement an actual "good enough" solution. –  iLikeDirt May 14 at 18:14

I would also offer as an alternative: a wider and flatter bucket. If you used a wide pan the evaporation rate would increase and might even be to the point of not needing to be emptied.

share|improve this answer
Depends on the climate. Somewhere soggy and cloudy like the UK, that might not make much of a difference. –  iLikeDirt Jul 2 '14 at 20:54
@DMoore:How wide/flat/big of a bucket/pan would I need to evaporate 3 Gallons / 12 L per day? That's how much water the A/C creates. –  ProgrammerGirl May 14 at 14:16
@ProgrammerGirl Knowing how much surface area it will take to passively evaporate the water depends directly on the climate of the area you live in. If you can specify where you live or at least share the average daily high temperature and dewpoint, that would assist the speculation. –  Jeff Meden May 14 at 17:12
@JeffMeden: On the hottest Summer months, the average relative humidity is about 72%, with about 9 mean daily sunshine hours, 1-2 inches of monthly rain, and daily mean temperatures of about 76 F / 24 C (with average highs of 84 F / 29 C). Remember, however, that the balcony only receives about 1 hour of direct sunlight, although plenty of hours of indirect sunlight. –  ProgrammerGirl May 14 at 17:57
Do you have a picture of the line and current setup? This would help us understand our options. –  DMoore May 14 at 17:59

Same solutions used for dehumidifiers should work: Let it drip into a tube run to somewhere appropriate (a drain, for example), or let it drip into a container that periodically pumps the water to somewhere appropriate. (My basement dehumidifier drains into the same pump that takes care of condensate from my boiler; its output hose is routed into the washing machine drain.)

Of course then you have a hose running through your apartment.

The only other thought I've got, assuming you can't join it into a rain gutter, would be to try to figure out how to route it so the water runs down the side of the building rather than being dumped out in midair. That would mostly keep it from falling on pedestrians.

Are there other occupants with air conditioners? Ask them how they've solved this.

share|improve this answer
The other occupants are also using buckets. Running hoses/pipes outside the balcony is not an option. –  ProgrammerGirl May 14 at 15:49
@ProgrammerGirl to that end I would suggest gathering a posse of other similarly annoyed residents and confront the management regarding just letting the AC units just drip down the side of the building like every other @#%$%$ apartment highrise since it can't be hard to find a large number of people suffering through the same exact frustration as you. –  Jeff Meden May 14 at 19:53

The solution for 100% closed cooling systems (like a refrigerator) is actually pretty elegant and simple: a pipe from the condenser coil (the part of the A/C on the "outside" that gets hot is run through a pan where water collected from the evaporator coil (the part that gets cold) sits. The fan that also cools the condenser blows over the water, which is now heating up because of the small part of the condenser coil in it, and the water evaporates into the "outside" air (i keep putting it in quotes because in the example of your refrigerator, its all indoor air, just outside the fridge).

Since you probably cant add a drain pan, are you at least close enough to the condenser unit for your apartment where you could let the water hit the condenser coil, and get heated and blown off by the already running fan? This might not take care of all of the water, but would at least increase the time it takes to fill the bucket up.

One more (probably obvious) thought is that the water is actually humidity from inside your apartment, condensing on the cold indoor coil of the AC unit, and collecting. If you decrease the outdoor air intrusion (better window seals, door seals, stoppers on dryer/bath vents, etc) you can ultimately decrease the amount of water the unit will pull out of the air.

And my final outside the box thought: can you just wait until no one is around, and then drain the bucket from your balcony? Like, if a timer went off automatically at 4am, and over the course of an hour it slowly drained the water down the side of the building, would anyone notice?

share|improve this answer
Here is a pic of the current setup: i.imgur.com/pGFKlgy.png How could I make the water hit the condenser coil/fan? Could that damage the machine? Emptying it at night would be risky due to potential fines. –  ProgrammerGirl May 14 at 18:25
The goal would be to get the water to sit on the condenser coil (the thing that looks like a car radiator) which is going to be warm and its going to have air blowing across it whenever the indoor unit is cold, which is a perfect recipe for evaporation. The outdoor unit is designed to be exposed to rain/dew so it is not going to be particularly bothered by some extra water, just try to avoid letting it drip directly on the fan. –  Jeff Meden May 14 at 18:36
Do you mean to do something like this: i.imgur.com/nVeBhKT.jpg (that's the drain line I just moved from the bucket and onto what I think is the condenser coil). If so, do you think that will be enough to evaporate all the water before it hits/drips to the floor? –  ProgrammerGirl May 14 at 18:57
A refrigerator is having to cool an entirely different type of space than an AC unit, thought. It's also not truly closed, and the condensate still leaves the confines of the fridge. –  DA01 May 14 at 19:17
Conceptually, I'd agree. Functionally, though, the change in scale is pretty significant. That's why you don't usually see 'condensate pans' on central air systems. They just dump it outside. There's just too much humidity being pulled out for a pan to be effective. –  DA01 May 14 at 21:48

How about running the condensate line into a humidifier?

You will want to get a humidifier that is ultrasonic (not "warm mist"), since you just wanted the water vaporized, not heated. Cut a small hole in the top of the tank, and run your condensate line into it.

Note that since this will be outside you will want to protect it somewhat from the weather, and definitely use a GFCI plug.

share|improve this answer
Which humidifier models can get get rid of 3 gallons of water per day? I've had trouble finding them. Also, how would I make the humidifier outdoor-proof besides using a GFCI plug? –  ProgrammerGirl May 14 at 18:02
Heres an example of a humidifier (albeit out of stock) that will vaporize 3 gallons/day: amazon.com/gp/product/B00005NT6B?tag=au026-20 and most of the other "cool mist" full size units from Crane or Honeywell do around 2.3 gallons/day. –  Jeff Meden May 14 at 18:27

There are lots of clever ideas here, but I think they are all over-engineered.

You simply need to get the water moved. Right now you are doing it manually with a bucket. I'd suggest some alternatives:

  1. Have the condensate line exit the building through the wall, extend it to ground level. This would be the simplest and cheapest route.
  2. Alternatively, you may not even have to extend it to ground level if you can have it exit the wall in a location that won't drip on anyone.
  3. Buy a small pump. Run a line from the bucket to a sink in the house. You can then either turn it on yourself once a day or get fancy with a sump-pump type switch that will turn on automatically when the bucket is full. This is pretty much how condensate pumps work on central air units.
  4. Buy a large dog. Have the condensate drain into his large water bowl. Granted, this means you now need to take the dog out more often. Not sure if that's easier than emptying the bucket. :)

Re: Humidifiers. Note that if you use a humidifier inside the house, you're defeating having the AC unit to begin with. A big benefit of an AC unit is that fact that it's dehumidifying the space for you. You want a dry cool, not a damp cool. An external humidifier could work. Though I can't imagine any humidifiers are designed for handling outside weather at all. Plus, now you have two appliances that need to be maintained.

share|improve this answer
The humidifier would be outside where the drain line and bucket are, not inside. –  ProgrammerGirl May 14 at 19:33
@ProgrammerGirl I can't say I know of any humidifiers rated for use outdoors. Could you show us a photo of the outside of your building? That might help us. –  DA01 May 14 at 19:35
I edited my post several hours ago with a pic. Please let me know your thoughts. –  ProgrammerGirl May 14 at 23:29

In your situation, I would set up an arduino powered automatic pump.


Basically, you put the water level sensor in the bucket. Once the sensor gets tripped, the arduino activates the relay, which turns on the pump. You pump until the sensor is satisfied. You can discretely run tubing from the pump to the bathtub/window/outside. No more bucket emptying!

P.S. If you search on a certain auction site, you can buy the sensor, relay, and arduino board for less than $15 total.

share|improve this answer

I see from your profile that you have previously asked questions about various configurations of ductless mini-split heat pumps, and that you have (or had) a Daikin model. Is this a unit you bought and installed yourself? If so, it seems that you have already violated the "no modifications" rule and presumably you could do it again to make a modification involving a flexible drain pipe or condensate pump, either of which could redirect the flow to a less objectionable location.

If, on the other hand, the A/C unit is owned and was installed by the apartment, it's eminently reasonable to ask them to come up with a solution. They can't set it up in a certain manner and then tell you that their install own results in an impermissible condition. That's just ridiculous.

share|improve this answer
The Daikins were for a different apartment. This apartment is a rental, already came with A/C, they explained the drainage limitation to me beforehand that I'm suffering now, so I'm trying to find some kind of solution that wouldn't require me to modify anything, such as some kind of super absorbent fast evaporator type device. –  ProgrammerGirl Jul 2 '14 at 20:28
The problem is that you need the evaporation to be outside... if going that route an ultrasonic mister does seem the best bet. Otherwise, we come back to either pumping the water across to a drain, or persuading it to run down the surface of the building, or finding some way to drain it into a rain downspout. –  keshlam May 15 at 0:36

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.