# Using Dehumidifier water?



## Sherminator (Aug 29, 2011)

I just recently got a dehumidifier for my basement (have had a water leakage issue that is going to be fixed shortly) to help dry it out. I was talking to my old man about it and he mentioned that the water is Distilled...which made me think about using it instead of getting RO water from the LFS.

I did a quick test with my TDS meter and I got a reading of 61 vs 215 or so with my tap water.

I'm willing to experiment with a small tank I have just set up (not to mention the TDS level is starting to get on the high side) but was curious as to see if anyone else has used dehumidifier water in their tanks.


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## Seattle_Aquarist (Jun 15, 2008)

Hi Sherminator,

I would strongly suggest against using it. Typically the water in a dehumidifier has a lot of dirt and contaminates that adhere to the coils that are used to remove the moisture. In addition it may have some oils and lubricants.


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## WallaceGrover (Jan 15, 2011)

Not so sure if it wouldn't be stagnant and have all sorts of icky microbes in it after sitting out in the resevoir...


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## hydrophyte (Mar 1, 2009)

I use it with my houseplants and they seem to love it. We have a lot of fluoride and hardness minerals in our tapwater.


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## CrazyMidwesterner (Oct 19, 2006)

I use it in my 75 G blackwater tank and no issues at all. I throw some prime in it just to be safe but all good so far.

Sent from my Transformer TF101 using Tapatalk


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## TexasCichlid (Jul 12, 2011)

Why not just get an undersink RO system?


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## Rich Conley (Jun 10, 2008)

WallaceGrover said:


> Not so sure if it wouldn't be stagnant and have all sorts of icky microbes in it after sitting out in the resevoir...


 
Fish tanks have all sorts of icky microbes in them.



The biggest thing to worry about here is metals. I remember testing water from a dehumidifier and finding it very high in copper. So it would be a no-no for shrimp. 

Also, lower TDS doesn't necessarily that there's less stuff in it. Particulate won't measure as dissolved.


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## MChambers (May 26, 2009)

I agree about the metal concern. Also, I once tested my dehumidifier water and found it had ammonia. I don't know how to explain this, but I got the results twice. And I know another person who had the same result. Prime should deal with the ammonia, of course, but I've decided that dehumidifier water is best used on house plants and not fish.


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## proaudio55 (Oct 20, 2011)

During the summer I use dehumidifier water to do water changes with no problems. The first year I ran my machine, all the water went down the drain. That was to let any flux / contaminants wash away. 1 year of use also lets the copper / metals oxidize (and become more stable)

I've used who-knows-how-many gallons of water out of it without any 'incidents.' Keep in mind that dehumidifiers aren't very efficient and I wouldn't run it just for the sake of making distilled water.


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## samjpikey (Oct 11, 2011)

Dehumidifiers are used to take moisture out of the atmosphere which is generally caused by damp , and damp is unwanted moisture which enables the growth of various fungi in wood and other materials , causing rot or can cause mold health issues , so would you really want to be putting this kind of water into a tank lol


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## ua hua (Oct 30, 2009)

Don't use water from your dehumidifier for your tank as others have said that their will be issues with metals and all other sorts of airborne contaminents such as mold/fungal spores and chemical contaminents because the water is obtained from the moisture in your air which has who knows what in it. If you don't want to waste the water from them you can always water your houseplants with it.


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## proaudio55 (Oct 20, 2011)

As for mold or fungus in there, I would assert that it shouldn't be a problem. These fish normally live in disease / malaria infested jungle. Anything growing in the dehumidifier is pretty tame in comparison.


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## ua hua (Oct 30, 2009)

proaudio55 said:


> As for mold or fungus in there, I would assert that it shouldn't be a problem. These fish normally live in disease / malaria infested jungle. Anything growing in the dehumidifier is pretty tame in comparison.


Fish in the wild are also on the verge of starvation so does that mean we shouldn't feed our fish. I think anybody keeping fish should try to keep them in the best conditions possible. I have been involved in this hobby for 25+ years and would not recommend using dehumidifier water for fish tanks but if you so choose to I hope all goes well.


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## kingb4c0 (Dec 9, 2009)

Don't see a valid point for use water from the dehumidifier, you want the best for your tank and minimize risks


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## samjpikey (Oct 11, 2011)

i think water in the wild is a bit different from water in the aquarium don't you?? after all we try our best to make our aquariums in a pristine condition , there for putting potential fungi (disease) riddled water is properly not a good idea .


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## CrazyMidwesterner (Oct 19, 2006)

samjpikey said:


> Dehumidifiers are used to take moisture out of the atmosphere which is generally caused by damp , and damp is unwanted moisture which enables the growth of various fungi in wood and other materials , causing rot or can cause mold health issues , so would you really want to be putting this kind of water into a tank lol


So water from a humidifier is mold causing, rot causing and disease riddled? Really? It's the same moisture you inadvertantly breathe in and out every day. If it causes mold it's because you have mold spores in your house, which if you do have it has probably already made into your tank. All water causes rot given time. Not specific to any special dehumidifier water. Disease???? 

Metals may be a concern. As far as I can tell with mine no issues but I use Prime which may help. Fish and shrimp are happy and healthy. Cherries are breeding like they do in my other tank. I've not had a single death in this specific tank to date. Granted it's been two months. I'll tell you about the long term when I get there  Also, I should note this dehumidifier has been in constant use for two years. It may have leached all it will leach.

Someone asked why not use RO water. Because its at least $150 for a setup and pointless if dehumidifier water works. 

Lastly, unless you have tried it and it caused an issue or if you have specific evidence why bother to comment? This forum cracks me up sometimes.


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## plantbrain (Dec 15, 2003)

I've used Dehum water to top off most of my tanks for well, about 6 years now........


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## AbbeysDad (Apr 13, 2016)

I realize that this is an old thread, but it popped up on a google search because of my situation. I have high nitrates in my well water due to a 95 acre farmers field across the road. So in addition to a nitrate filter I made using API Nitra-Zorb and an API Tap Water Filter housing, I had been using water from my dehumidifier. After all, it's just moist air condensed over refrigerated coils so it should be as pure as distilled water...or so I thought. After a partial water change using a more or less 50/50 mix of 'good' water and the reclaimed water, I noticed the fish in distress. Some clamped fins, flashing and fish gulping air at the surface. A test revealed ammonia of .25-.50ppm.
Prime saved the day. After some head scratching and double testing with controls I ruled out the API test chems and determined that the dehumidifier water was 4-8ppm (were're talking really dark green). I don't understand how this water, even fresh from the unit can be so toxic...but it is.
I'll obviously no longer be using it!


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## Bandit1200 (Dec 11, 2010)

Not to detract from your fishes distress, but that has me intrigued... If I had a dehumidifier it seems I could kill 2 birds with one hammer. I could top off the tank and add nitrates at the same time. Down here in the Gulf Coast there's always room for a dehumidifier in addition to the air conditioning. I've been considering adding one to the house anyway to take some of the load off the main a/c.


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## AbbeysDad (Apr 13, 2016)

Bandit1200 said:


> Not to detract from your fishes distress, but that has me intrigued... If I had a dehumidifier it seems I could kill 2 birds with one hammer. I could top off the tank and add nitrates at the same time. Down here in the Gulf Coast there's always room for a dehumidifier in addition to the air conditioning. I've been considering adding one to the house anyway to take some of the load off the main a/c.


I don't think you want to add toxic ammonia just to save a little on ferts. Besides, after discovering ammonia in what I thought would be pure water, I have to wonder what other evil might be in there - copper or other heavy metal or who knows what. My research that led me to this old thread suggests a lot of people find that dehumidifier water contains high levels of ammonia.
I won't be using it again, but hey, if you get one, test the water and see what you get.
*Edit Footnote: My basement dehumidifier, although cleaned, is several years old. Newer units (materials) and/or different models may produce better (purer) water.*


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## ichy (Apr 6, 2015)

Rich Conley said:


> Fish tanks have all sorts of icky microbes in them.
> 
> 
> 
> ...


Ya that water is dripping off copper coils. I would avoid it just for that reason.

If you want pure water get an ro unit, they are a dime a dozen around here on Craigslist. And where are you going to get that water in the winter when you aren't running the dehumidifier?

You may need to swap in new filters on a used unit, but if you can pick one up cheap you will be ahead.


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## AbbeysDad (Apr 13, 2016)

ichy said:


> Ya that water is dripping off copper coils. I would avoid it just for that reason.
> 
> If you want pure water get an ro unit, they are a dime a dozen around here on Craigslist. And where are you going to get that water in the winter when you aren't running the dehumidifier?
> 
> You may need to swap in new filters on a used unit, but if you can pick one up cheap you will be ahead.


Hmm...Since all the supply lines in my house are lead soldered copper, I'm not sure how water dripping off a copper coil would be a problem or let alone create a high level of ammonia! Besides, I'm not sure but I think the coils in my whirlpool dehumidifier are aluminum.

The inexpensive RO units (around $150) tend to be short lived or unreliable. RO units require a 50 - 80 psi supply to force water through the membrane. My well system is on a 30/50psi controller so I'd need some additional pump to make it work. Then it needs to be plumbed to a waste line as there's 4 gallons of waste water for every gallon of RO water produced. Then there's the chems required for minerals and pH adjustment. So, at least for me, I'd prolly need about $500 for a decent RO system when all I really need to do is filter out nitrates.


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## Nordic (Nov 11, 2003)

It is not that the water it gets from the air is dirty.
But in the machine you have metal coils and whatnots, that is covered in moisture and probably bacteria, as that is what you get when you leave anything moist long enough. Water condenses on this, slowly flows by/through it using only gravity, pulling some of the nasty stuff along with it.


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## AbbeysDad (Apr 13, 2016)

Nordic said:


> It is not that the water it gets from the air is dirty.
> But in the machine you have metal coils and whatnots, that is covered in moisture and probably bacteria, as that is what you get when you leave anything moist long enough. Water condenses on this, slowly flows by/through it using only gravity, pulling some of the nasty stuff along with it.


The odd thing (I thought) was the 4.0 - 8.0ppm ammonia (closer to 8.0) in the water.


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## Nordic (Nov 11, 2003)

I guest dust and debris decaying in there would be adding to it, but it does seem high.


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