Extract Water from Air: DIY Methods & Solutions

  • Thread starter perplexabot
  • Start date
  • Tags
    Air Water
In summary: They can be made with materials found in nature and can be relatively inexpensive. However, it may require some trial and error to find the right design that works for your specific location and needs.
  • #1
perplexabot
Gold Member
329
5
Hello all. So I am trying to see if it is possible to build a device that is able to extract water from the surrounding air. I know there are a couple of systems that already do that (based on condensation), some active and some passive, such as the atmospheric water generator (this device is tooooo expensive though) and air wells.
As little as 50mL of water per day will do (more will be better).

I read somewhere that a dehumidifier can be used to extract water from air (but that can cost around $200), worst comes to worst, i might have to go with this method.

I also read how air well's work, but cannot come up with a decent method.

Can anyone provide me with a link or method that may be able to help achieve what is needed (assuming my goal is achievable)? Primitive methods are okay as long as the system is somewhat portable.
 
Last edited:
Engineering news on Phys.org
  • #2
Dehumidifier, not humidifier. By definition, that is the device you are looking for. There are several methods, but the most common is refrigeration.

You haven't really told us what your goal is though, so it will be tough to help without more info:
-How much water?
-What are the starting conditions of the air?
-What is your budget?
-Other constraints?
 
  • #3
perplexabot said:
Hello all. So I am trying to see if it is possible to build a device that is able to extract water from the surrounding air. I know there are a couple of systems that already do that (based on condensation), some active and some passive, such as the atmospheric water generator (this device is tooooo expensive though) and air wells.
As little as 50mL of water per day will do (more will be better).

I read somewhere that a humidifier can be used to extract water from air (but that can cost around $200), worst comes to worst, i might have to go with this method.

I also read how air well's work, but cannot come up with a decent method.

Can anyone provide me with a link or method that may be able to help achieve what is needed (assuming my goal is achievable)? Primitive methods are okay as long as the system is somewhat portable.

What is the range of relative humidity (RH) in the locations where you want to do this?
 
  • #4
Hey, thanks for the quick replies. Oops, I meant dehumidifier, will fix OP, thank you. My goal is to use that water for plants (irrigation). According to a quick google search, the amount of water needed on average (per day) for a petunia is around 50mL (ideally I would water more than one plant, so maybe .3L for 6 plants?.. Essentially, the more the better).

I know there is a way to calculate water needed for plant (using evapotranspiration), but I feel a quick estimate just to get me started on this "air to water" device will do for now.

A quick google for my local humidity shows 9-13% moisture (would this be the 'relative' humidity you were asking about?)

Budget: less than $100 would be nice.

Other constraints:
Want to power using 10W solar panel (2 if need be) [assuming a active component]
 
  • #5
Holy smokes, 9-13% RH is dry! You live in a desert?

Would drilling a small well be another option?
 
  • #6
berkeman said:
Holy smokes, 9-13% RH is dry! You live in a desert?

Would drilling a small well be another option?

Ahaha. I live ~10mi from the beach. No, I can't drill. The device would have to be somewhat portable...

Is there a way to know how much water you can get from 10% humidity, on average per day?
 
  • #7
  • Like
Likes 1 person
  • #8
If you are that close to water, RH should be higher than 9-13%.
 
  • Like
Likes 1 person
  • #9
berkeman said:
The wikipedia article on dehumidifiers looks pretty good: http://en.wikipedia.org/wiki/Dehumidifier

Note what it says about watering vegetables with recovered water -- probably doesn't apply to flowers though.

Nice catch. I think that is a no for the dehumidifier then. I may need to use this water for vegetables. This may be harder than I thought.
 
  • #10
Borek said:
If you are that close to water, RH should be higher than 9-13%.

If I google "humidity in Irvine," I get 10% Humidity : (
 
  • #11
perplexabot said:
Nice catch. I think that is a no for the dehumidifier then. I may need to use this water for vegetables. This may be harder than I thought.

Wikipedia also has info about Atmospheric Water Generator, which generates potable water:

http://en.wikipedia.org/wiki/Atmospheric_water_generator

.
 
  • Like
Likes 1 person
  • #12
perplexabot said:
If I google "humidity in Irvine," I get 10% Humidity : (

Looks like it makes it up to 30% around 6AM though. Still, it does look pretty dry. Are there hills between Irvine and the beach?
 
  • Like
Likes 1 person
  • #13
berkeman said:
Wikipedia also has info about Atmospheric Water Generator, which generates potable water:

http://en.wikipedia.org/wiki/Atmospheric_water_generator

.

Yes, I have already looked into that (as I mentioned in my OP). It costs at least $600 on amazon, that is way over my budget.
 
Last edited:
  • #14
berkeman said:
Looks like it makes it up to 30% around 6AM though. Still, it does look pretty dry. Are there hills between Irvine and the beach?

Yes, there are hills. But again, it has to be portable.
 
  • #16
Borek said:
http://www.usa.com/irvine-ca-weather.htm

Annual average of 80.04%.

Thanks for the link. I think if this device works with the current weather, then it should work throughout the year (according to your link), roughly speaking (except for April! the graph for humidity in irvine is very interesting, something weird happens in April! anyway that is completely off topic)

Maybe somekind of primitive air well system would work?
 
  • #17
Dehumidifiers do not do anything except generate heat when the humidity is low like it is in winter. Point of order though; it is absolute humidity that matters, not relative humidity. A dehumidifier's coil operates at a specific temperature, resulting in a specific dew point for the air moving over it.

What you are proposing here is an extremely expensive way to generate water. Is there a particular reason why you would not just use tapwater?
 
  • #18
russ_watters said:
What you are proposing here is an extremely expensive way to generate water. Is there a particular reason why you would not just use tapwater?

No, I was just wondering if it was possible to do so with a low budget, but the more I research the more I realize this is not possible.

Actually, I just found this:
https://www.amazon.com/dp/B0069ABM7A/?tag=pfamazon01-20

I wonder if this is what I am looking for, it is cheap too. Do you think it is worth checking out?

EDIT:
It says it is around 20Watts and produces around 8oz/day (80% relative humidity). This may work, I wonder how much with the current weather.
 
Last edited:
  • #19
perplexabot said:
Actually, I just found this:
https://www.amazon.com/dp/B0069ABM7A/?tag=pfamazon01-20

I wonder if this is what I am looking for, it is cheap too. Do you think it is worth checking out?

EDIT:
It says it is around 20Watts and produces around 8oz/day (80% relative humidity). This may work, I wonder how much with the current weather.
80% RH at 86F is extremely humid.
 
  • #20
russ_watters said:
80% RH at 86F is extremely humid.

I will be satisfied if I get as little as 50mL of water. I will order it and see how much water it will yield/day
 
  • #21
What is 5 gallons divided by 50mL?
 
  • #22
berkeman said:
What is 5 gallons divided by 50mL?
5 gallons = 18927.1 mL

(18927.1 mL) / (50 mL) = 378.5 ?

Why?
 
  • #23
perplexabot said:
5 gallons = 18927.1 mL

(18927.1 mL) / (50 mL) = 378.5 ?

Why?

How often will you visit this garden? :smile:
 
  • #24
berkeman said:
How often will you visit this garden? :smile:


Say once a month, preferably less. Why :confused: ?
 
  • #25
perplexabot said:
Say once a month, preferably less. Why :confused: ?

378.5 / 31 = ??

Why would you not just carry out a 5 gallon water bottle to your automated watering system each month instead? It's good that you're exploring the options, but at this point, the math should be pretty clear hopefully. BTW, I have learned from this thread as well. :smile:
 
  • Like
Likes 1 person
  • #26
perplexabot said:
I will be satisfied if I get as little as 50mL of water. I will order it and see how much water it will yield/day
Unfortunately, you will get absolutely nothing out of it until spring.
 
  • #27
berkeman said:
378.5 / 31 = ??

Why would you not just carry out a 5 gallon water bottle to your automated watering system each month instead? It's good that you're exploring the options, but at this point, the math should be pretty clear hopefully. BTW, I have learned from this thread as well. :smile:

Ahahaha, i see what you are saying. Yes, if this "water from air" plan doesn't work, using a 5 gallon bottle or tap water will be what I will resort to. For now I still have time to see if this is achievable.

EDIT: Glad to hear you learned something too : ) Thank you for your help.
 
Last edited:
  • #28
russ_watters said:
Unfortunately, you will get absolutely nothing out of it until spring.

First, are you saying, with complete certainty, that if I were to order that dehumidifier (link shown previously) and have it operate during current weather conditions I will get absolutely no water?

Another question, the link I provided was of a mini dehumidifier, there is another that is double the price ($88, still cheap). Here is the manual: http://www.eva-dry.com/media/rte/manuals/edv-2200-manual.pdf [Broken]

It says it operates at a whopping 72Watts and produces 20oz/day at 86F and 80% humidity.
The question being, would bigger be better in this case? Would a larger dehumidifier produce more water than a smaller one under the same conditions?

Problem with a 72Watt component is I would need a ~75Watt Solar panel. That still isn't too bad.

EDIT: Is there a way to calculate how much water that machine will produce in my environment?
 
Last edited by a moderator:
  • #30
perplexabot said:
First, are you saying, with complete certainty, that if I were to order that dehumidifier (link shown previously) and have it operate during current weather conditions I will get absolutely no water?
There can never be complete certainty about anything, but I'm 90% sure.

The way a dehumidifier works is that it has a surface that is colder than the current dew point of the air. That causes water to condense onto the surface. A 20W dehumidifier almost certainly uses a peltier cooler (the manual you linked confirms that for the other one), which may have a pretty cool surface, but to avoid frosting over, it will have to be above freezing.

Currently, the dew point in Irvine is 34 F, which means that if the surface temperature of your dehumidifier is above 34 F, you'll get nothing. Below 32F, you'll get ice and not water. For reference, the design conditions of 80% RH at 86F is a dew point of about 80F.
It says it operates at a whopping 72Watts and produces 20oz/day at 86F and 80% humidity.
The question being, would bigger be better in this case? Would a larger dehumidifier produce more water than a smaller one under the same conditions?
Yes, of course. The difference is strictly the surface area of the cold plate, which is what water condenses on. 3x the wattage means 3x the surface area and 3x the water condensing on it.
EDIT: Is there a way to calculate how much water that machine will produce in my environment?
Yes. It is a little involved and I have to leave for work in a few min, but I'll get back to you on it.
 
  • #31
This is a lot of what I do for a living (HVAC engineering), so I have some tools available at work I can use to help.

The thermodynamics of air is a science called psychrometrics: http://en.wikipedia.org/wiki/Psychrometrics
The wiki has a sample chart and there are apps you can download or us online to plug in some conditions and get the rest. I use this one: http://www.tranecds.com//COMMERCIAL/DNA/View.aspx?i=1250

So the humidifier generates 20.5 oz per day (0.053 lb/hr) of moisture from 86F air at 80% RH. Plugging into a psychrometric chart gives a dew point of 79F and an absolute humidity of 152 grains (I'll explain that in a min...).

According to published climate data I have, the most humid it ever gets in absolute terms in Irvine (.4% of the time) is a dew point of 70F at 79 degrees (111 grains per pound of air). So we'll try to calculate the peak real output of this dehumidifier that you'll see for those 35 hours a year. By comparison, the most humid areas in the US are in the rainforests of southern Florida, where they get a dew point of up to 81F (matching the desing conditions of your dehumidifier).

A dehumidifier works by cooling air down below its dew point, squeezing moisture out as it does. The surface temperature of the peltier device in the dehumidifier is probably about 40F to avoid freezing. This will vary though; a little lower when it is cooler and drier, a little higher when it is warmer and wetter. That temperature will also vary with airflow, so if the dehumidifier gets clogged with dust, that temperature will also drop. For our calcs, we'll assume it is a constant 40F (37 grains).

The amount of moisture in the air is absolute humidity. For laymen, it is the dew point; your dehumidifier lowers the temperature and therefore dew point of the air flowing through it from our starting point of 70F to 40F. In psychrometrics, absolute humidity is measured in grains, which is the actual mass of water in air: 1 grain is 1/7000th of a pound. Relative humidity is the ratio between the moisture carrying capacity of the air (which varies with temperature) and the actual amount of moisture.

So your dehumidifier will drop the moisture in the air from 111 grains per pound to 37 grains per pound. Or, for every pound of air that moves through it, (152-37)/7000 = 0.016 lb of moisture will be squezed out. So that requires an airflow of 0.053 / 0.016 = 3.3 lb per hour (about 0.7 cubic feet per minute).

Reversing the calcultion using your acutal humidity yields (111-37)/7000 * 3.3 = 0.035 lb / hr or 13 ounces per day.
 
  • #33
First of all thanks to everyone for helping out and for the many good ideas and suggestions. Physics forums is where all the cool people are at :cool:

Borek said:
Check https://blumatsystems.com/category/3/Tropf-Blumat-Drip-Blumat

We used them here. They worked nicely in the winter, but were unable to keep up in the summer. However, perhaps using two or a larger model will do the trick, we never checked.
Interesting component. Not exactly what I need though, but may come in handy at some point. Thanks.

russ_watters said:
This is a lot of what I do for a living (HVAC engineering), so I have some tools available at work I can use to help.

The thermodynamics of air is a science called psychrometrics: http://en.wikipedia.org/wiki/Psychrometrics
The wiki has a sample chart and there are apps you can download or us online to plug in some conditions and get the rest. I use this one: http://www.tranecds.com//COMMERCIAL/DNA/View.aspx?i=1250

So the humidifier generates 20.5 oz per day (0.053 lb/hr) of moisture from 86F air at 80% RH. Plugging into a psychrometric chart gives a dew point of 79F and an absolute humidity of 152 grains (I'll explain that in a min...).

According to published climate data I have, the most humid it ever gets in absolute terms in Irvine (.4% of the time) is a dew point of 70F at 79 degrees (111 grains per pound of air). So we'll try to calculate the peak real output of this dehumidifier that you'll see for those 35 hours a year. By comparison, the most humid areas in the US are in the rainforests of southern Florida, where they get a dew point of up to 81F (matching the desing conditions of your dehumidifier).

A dehumidifier works by cooling air down below its dew point, squeezing moisture out as it does. The surface temperature of the peltier device in the dehumidifier is probably about 40F to avoid freezing. This will vary though; a little lower when it is cooler and drier, a little higher when it is warmer and wetter. That temperature will also vary with airflow, so if the dehumidifier gets clogged with dust, that temperature will also drop. For our calcs, we'll assume it is a constant 40F (37 grains).

The amount of moisture in the air is absolute humidity. For laymen, it is the dew point; your dehumidifier lowers the temperature and therefore dew point of the air flowing through it from our starting point of 70F to 40F. In psychrometrics, absolute humidity is measured in grains, which is the actual mass of water in air: 1 grain is 1/7000th of a pound. Relative humidity is the ratio between the moisture carrying capacity of the air (which varies with temperature) and the actual amount of moisture.

So your dehumidifier will drop the moisture in the air from 111 grains per pound to 37 grains per pound. Or, for every pound of air that moves through it, (152-37)/7000 = 0.016 lb of moisture will be squezed out. So that requires an airflow of 0.053 / 0.016 = 3.3 lb per hour (about 0.7 cubic feet per minute).

Reversing the calcultion using your acutal humidity yields (111-37)/7000 * 3.3 = 0.035 lb / hr or 13 ounces per day.
Wow. First of all, I definitely learned a lot from that post so I want to thank you for that. I was able to follow the math up until you calculating air flow : ( Will get back to it again, for sure. So according to your calculations the max yield (which is only 35hrs a year!) is around 13oz/day.
So I am assuming, I should be able to follow your calculations (and use the table) to see how much water this dehumidifier will obtain for my current weather?

I will give it a go.
PS: That is one crazy looking chart :eek:
 
  • #34
Ok, so here it goes:
Given: average temperature = 70F and average humidity = 13%
Plugging DB=70F and RH=13%, I get W = 21.4 (grain)
W < 37 => On average I will get nothing out of the dehumidifier, under current weather conditions.
Is that true?
 

1. How does extracting water from air work?

Extracting water from air involves using a variety of methods to condense water vapor in the air into liquid form. This can be done through cooling, desiccation, or using specialized materials such as hydrophilic surfaces. The water is then collected and purified for use.

2. What materials are needed for a DIY air-to-water extraction system?

Materials needed for a DIY air-to-water extraction system may include a container for collecting the water, a cooling or desiccation mechanism, a fan or pump, and a filtration system. The specific materials and setup will depend on the method being used.

3. Is it safe to drink water extracted from air?

Yes, as long as the extraction process is done correctly and the water is properly filtered and purified. However, it is important to note that the quality of the water will depend on the air quality in the surrounding environment.

4. Can I use this method to extract water in any climate?

Yes, the method of extracting water from air can be used in any climate. However, the effectiveness and efficiency of the process may vary depending on the humidity levels in the air. Higher humidity levels will result in more water being extracted.

5. How much water can be extracted from air using DIY methods?

The amount of water that can be extracted from air using DIY methods will vary depending on the specific method and materials used, as well as the humidity levels in the air. Some methods may only produce a small amount of water, while others may be able to produce several liters per day.

Similar threads

Replies
25
Views
2K
  • General Engineering
Replies
9
Views
4K
Replies
11
Views
2K
  • General Engineering
Replies
3
Views
1K
  • General Engineering
2
Replies
51
Views
5K
  • General Engineering
Replies
1
Views
783
Replies
2
Views
2K
Replies
14
Views
2K
Replies
18
Views
2K
  • General Engineering
Replies
23
Views
2K
Back
Top