Reusing Dehumidifier Water into The Humidifier?

SunshineSupergirl · Jan 29, 2025

I had an idea.

If I get a dehumidifier that has a drain hose, I was wondering if I could run the water from that drain hose to a hole in my humidifier and essentially recycle the water for a while.

(but obviously still cleaning and adding fresh water every so often)

Is that feesable?

Has anyone ever tried doing this?

I know I could also drain the water back into my plants as another option, instead of having to drain the tank all the time.

Thoughts?

LoveGrowingIt · Jan 29, 2025

SunshineSupergirl said:
Is that feasible?

I do it, but it only works when there's a lot of humidity because loss to the atmosphere is significant. I dump my dehumidifier into a 5-gallon bucket and then fill my humidifiers from it. I figure it's better than pouring the water down the drain. There just isn't enough of it to be the only source of water for the humidifiers.

SunshineSupergirl said:
I know I could also drain the water back into my plants as another option, instead of having to drain the tank all the time.

Check the pH before you do. It can be acidic. CO2 in the atmosphere can create carbonic acid.

SunshineSupergirl · Jan 29, 2025

LoveGrowingIt said:
I do it, but it only works when there's a lot of humidity because loss to the atmosphere is significant. I dump my dehumidifier into a 5-gallon bucket and then fill my humidifiers from it. I figure it's better than pouring the water down the drain. There just isn't enough of it to be the only source of water for the humidifiers.

Check the pH before you do. It can be acidic. CO2 in the atmosphere can create carbonic acid.

I like the idea of recycling the water to the humidifier.

But I'm assuming that I would also need to check that water too every now and then and replace it with fresh water.

I was also planning on adding a small two bottle system of yeast and sugar to create extra CO2.

So probably best not to actually put that water into the plants just straight back into the humidifier.

carlosescobar · Jan 29, 2025

SunshineSupergirl said:
I like the idea of recycling the water to the humidifier.

But I'm assuming that I would also need to check that water too every now and then and replace it with fresh water.

I was also planning on adding a small two bottle system of yeast and sugar to create extra CO2.

So probably best not to actually put that water into the plants just straight back into the humidifier.

I messed around with sugar and yeast for a while but i find baking soda and vinegar is much easier

SunshineSupergirl · Jan 29, 2025

carlosescobar said:
I messed around with sugar and yeast for a while but i find baking soda and vinegar is much easier

Doesn't it release quicker though?

Wouldn't you have to replace it more often?

Is there a way to make it more slow release?

Natep · Jan 30, 2025

You need tor run both? I live in Southern California. It is crazy dry here been all the way down to 13% rh. I have to run humidifiers year round. I’ve never needed a dehumidifier. I find it strange you would need both. Must be crazy humidity swings there.

SunshineSupergirl · Jan 30, 2025

Natep said:
You need tor run both? I live in Southern California. It is crazy dry here been all the way down to 13% rh. I have to run humidifiers year round. I’ve never needed a dehumidifier. I find it strange you would need both. Must be crazy humidity swings there.

San Francisco experiences humidity from 52 to 80% most of the time.

Some days it's 100%

Especially now during the rainy season.

Occasionally it's REALLY dry here but it's rare.

We have a vortex of cold air that comes in the bay that brings in all that moisture from the Arctic and it funnels it right into East Bay which makes us humid and a little bit cold sometimes but usually just warm.

SunshineSupergirl · Jan 30, 2025

Like today.

This is the usual average of Humidity in the city.

Natep · Jan 30, 2025

SunshineSupergirl said:
San Francisco experiences humidity from 52 to 80% most of the time.

Some days it's 100%

Especially now during the rainy season.

Occasionally it's REALLY dry here but it's rare.

We have a vortex of cold air that comes in the bay that brings in all that moisture from the Arctic and it funnels it right into East Bay which makes us humid and a little bit cold sometimes but usually just warm.

Seems like you would need mostly dehumidifiers.

TheDankest · Jan 30, 2025

Natep said:
You need tor run both? I live in Southern California. It is crazy dry here been all the way down to 13% rh. I have to run humidifiers year round. I’ve never needed a dehumidifier. I find it strange you would need both. Must be crazy humidity swings there.

Come try out a grow in New England, you'd be in for a treat with the humidity fluctuations here

I need a humidifier in late Fall/Winter and a dehumidifier during Spring/Summer here

PooToe · Jan 30, 2025

I setup my dehu to dump back into my 30 gal reservoir when I needed to leave for an extended period of time. I figured it could top off the tank and dilute down the PPM's which is what I do anyways. I was gone 6 weeks and had someone come in at week 4 to check. They added a few gallons as the res was running a bit low but for the most part the dehu kept the res topped off or at least slowed having to top off.

Some say that the metal grid where the condensation collects adds harmful metals to the water but I had my dehu condensate tested and no heavy metals other than what was normal for tap water in the area.

When I'm not using the dehu to top off the res I use a refrigerator condensate pump to pump out the condensate into my garden.

When I got back I checked the reservoir.Tthere was around 15 gallons of feed solution left. PPM was at 380. pH was at 6.4. I started the res at 1200ppm with a pH of 6.5.

LoveGrowingIt · Jan 30, 2025

PooToe said:
Some say that the metal grid where the condensation collects adds harmful metals to the water but I had my dehu condensate tested and no heavy metals other than what was normal for tap water in the area.

Metals are unlikely. Acidification is possible, though. The water combines with CO2 in the atmosphere to produce carbonic acid. Years ago, I tested the water in my dehumidifier tank because I was curious to see if it was like distilled water with a pH of 7.0. It instead had a pH of 4.4. I didn't find much information about it, but did learn that not all dehumidifiers do it. So, I just tell people to test the pH before using it for plants.

Putthataway · Jan 30, 2025

My dehumidifier instructions state the water will contain bacteria. Someone else on this forum mentioned his said it would contain heavy metals.

SunshineSupergirl · Jan 30, 2025

TheDankest said:
Come try out a grow in New England, you'd be in for a treat with the humidity fluctuations here

I need a humidifier in late Fall/Winter and a dehumidifier during Spring/Summer here

We get some hot and dry weather September and October, usually.

Glassdub · Jan 31, 2025

Check the pH it's usually 3 or less, acid, so no.

SunshineSupergirl · Jan 31, 2025

Glassdub said:
Check the pH it's usually 3 or less, acid, so no.

I'm playing it safe and I'm just going to recycle it into the humidifier reservoir.

Only when I'm gone though, for extended periods.

PooToe · Jan 31, 2025

SunshineSupergirl said:
I'm playing it safe and I'm just going to recycle it into the humidifier reservoir.

Only when I'm gone though, for extended periods.

Uh....if you're worried about the condensate being too acidic to feed to the plants why would you want to spray acid into the air?

SunshineSupergirl · Jan 31, 2025

PooToe said:
Uh....if you're worried about the condensate being too acidic to feed to the plants why would you want to spray acid into the air?

I'll have to check the water for the humidifier too then.

But I'm guessing since it won't go directly in soil it shouldn't be a concern.

Previous poster said all dehumidifiers are different.

Mathimus · May 24, 2025

Yes, your dehumidifier waste is basically RO water. I use it for my seedlings and clones. It works.

Reusing Dehumidifier Water into The Humidifier?

Reusing Dehumidifier Water into The Humidifier?

SunshineSupergirl

LoveGrowingIt

SunshineSupergirl

carlosescobar

SunshineSupergirl

Natep

SunshineSupergirl

SunshineSupergirl

Natep

TheDankest

PooToe

LoveGrowingIt

Putthataway

SunshineSupergirl

Glassdub

SunshineSupergirl

PooToe

SunshineSupergirl

Mathimus

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