Water-from-Air Frequently Asked Questions
Question. Do minerals need to be added to water with a low mineral content [such as drinking-water-from-air]?
At least two credible organizations have reported on this topic; the Water Quality Association (WQA) and the World Health Organization (WHO). Read both reports to make your own informed decisions for your water-from-air projects.
Excerpt from WQA Technical Guidance: "Worldwide, there are no agencies having scientific data to support that drinking water with low TDS [Total Dissolved Solids] will have adverse health effects. There is a recommendation regarding high TDS, which is to drink water with less than 500mg/L. Some people speculate that drinking highly purified water, treated by distillation, reverse osmosis, or deionization, “leaches” minerals from the body and thus causes mineral deficiencies with subsequent ill health effects." (from Water Quality Association, International Headquarters and Laboratory, Lisle, Illinois, USA; read their 7-page report titled Consumption of Low TDS Water)
WHO assessment: WHO—Calcium and magnesium in drinking-water
How do I compare the effectiveness of competing methods of obtaining water from the air?
Comparisons are possible if the equipment provider has stated water production capacity and energy input of their device at the standard conditions of 26.7 degrees C (80 degrees F) and 60% relative humidity. These are the standard conditions used by the dehumidification industry. The reference publication is AHAM DH-1-2008, Dehumidifiers, by the Association of Home Appliance Manufacturers.
Would the quality and quantity of water produced from air change depending on air quality (pollution index)?
Water quality is affected by air quality. For example, while operating a water-from-air machine in a region of eastern Canada, where electricity is produced by coal-fired plants, water quality tests revealed a trace of strontium in the product water of the machine. Although we did not test the air, we surmised the ambient air contained traces of strontium from combustion of coal. Strontium was not detected in product water while testing several machines in western Canada where electricity is from hydro-electric sources. Volatile organic compounds (VOCs) in the entering air can also pass through the system into the product water unless one or more VOC filters are added to the water flow path. Particulates in the ambient air can be removed by air filters before the air enters the water-from-air processing system. Sediment filters can be inserted into the water flow path to remove fine particulates not removed by the air filter. Before starting long-term use of water-from-air product water at a site, it is wise to have a sample of the product water tested by a reputable laboratory to ensure the water quality meets national or World Health Organization water quality guidelines. Tests should be scheduled annually to verify that water quality remains acceptable.
Would the quantity of water produced vary on a day to day basis?
Yes, water production rate depends on the water vapour density ("absolute humidity") of the ambient air. The water vapour density changes according to weather conditions related to characteristics of the air masses passing through the region in which the water-from-air machine is located. Day-to-day variability is minor usually but month-to-month and seasonal variability can be substantial, especially in temperate climates.
Given the fact that water quality is affected by air quality, how then would one market this product in a third world country? Would any one manufacturer need to do air quality analyses in each interested market (country) before soliciting its business? Thank you. A concerned distributor.
The manufacturer and its distributors should be aware of air quality conditions in each market area. Air quality could be different in the same city. The city's suburbs are likely to have better air quality than its industrial areas. Alternatively, prevailing winds may keep industrial or zones with heavy vehicle traffic relatively unpolluted while suburbs downwind are enveloped in polluted air. Ultimately,it is more effective to test water quality than air quality—it is the end result that counts. A responsible distributor of water-from-air machines (perhaps sharing costs with the manufacturer) should do an annual test of the water from at least one representative machine from each "air-shed" of their market area. This comprehensive test should include inorganic parameters, organic parameters, and physical parameters. Testing should also be done for microbes. If nuclear power plants are nearby, it would be wise for the testing to include radio-logical parameters. Although this type of water testing is expensive, a proportion could be factored into the selling price of the machines at both the manufacturer's and distributor's levels, or into maintenance contracts, so that there is no financial-based excuse for not performing the annual tests. The end-users should not be expected to do the testing. The manufacturer and distributor must bear the responsibility as part of their role as water-from-air technology providers in their region. If problems with the water quality are found, the end-users must be notified immediately. Therefore, best efforts must be made to maintain up-to-date lists of machine owners—just as automobile dealers and manufacturers keep track of customers in case there has to be a recall for defective vehicles. Specific filters, such as for volatile organic compounds (VOCs) may have to be added to machines in some market areas. Although all this may come across as discouraging, keep in mind that many regions where water-from-air machines are practical are likely to have relatively clean air. The increasing need to use water-from-air machines is yet another reason for all people to treat our "atmospheric-commons" with respect and not use the atmosphere as a dumping place for waste products of our activities.
How much energy is used to produce a liter of water in optimal conditions?
First let us say that optimal conditions = standard test conditions for dehumidifiers which is 26.7 C dry bulb air temperature, relative humidity 60%, and air pressure at one atmosphere. Under these test conditions, I have found both through modeling and real world measurement experience that 20 L/day machines consume 0.68 kWh per litre of water produced. Larger machines, typically rated at 2500 L/day consume 0.4 kWh per litre of product water. This is because the larger machines are more efficient at using the atmosphere as a heat sink. It is interesting to note that in natural systems, the energy consumed to change the phase of water from gas to liquid (enthalpy of vaporization, formery called 'latent heat') is 0.681 kWh per litre.
Is there a solar pv component to provide energy to the WFA device?
At this time, the cost of solar PV systems remains too high to be feasible to use with water-from-air systems. Sufficient battery storage must be part of the system to allow 24 hour operation. Every hour of operation is precious because of the relatively low rate at which water-from-air systems process water vapour into liquid water.
Are these products/devices currently being produced and distributed?
Several manufacturers are producing and distributing water-from-air systems at various scales. I have compiled a list of links to manufacturers. Caveat emptor.
At least two credible organizations have reported on this topic; the Water Quality Association (WQA) and the World Health Organization (WHO). Read both reports to make your own informed decisions for your water-from-air projects.
Excerpt from WQA Technical Guidance: "Worldwide, there are no agencies having scientific data to support that drinking water with low TDS [Total Dissolved Solids] will have adverse health effects. There is a recommendation regarding high TDS, which is to drink water with less than 500mg/L. Some people speculate that drinking highly purified water, treated by distillation, reverse osmosis, or deionization, “leaches” minerals from the body and thus causes mineral deficiencies with subsequent ill health effects." (from Water Quality Association, International Headquarters and Laboratory, Lisle, Illinois, USA; read their 7-page report titled Consumption of Low TDS Water)
WHO assessment: WHO—Calcium and magnesium in drinking-water
How do I compare the effectiveness of competing methods of obtaining water from the air?
Comparisons are possible if the equipment provider has stated water production capacity and energy input of their device at the standard conditions of 26.7 degrees C (80 degrees F) and 60% relative humidity. These are the standard conditions used by the dehumidification industry. The reference publication is AHAM DH-1-2008, Dehumidifiers, by the Association of Home Appliance Manufacturers.
Would the quality and quantity of water produced from air change depending on air quality (pollution index)?
Water quality is affected by air quality. For example, while operating a water-from-air machine in a region of eastern Canada, where electricity is produced by coal-fired plants, water quality tests revealed a trace of strontium in the product water of the machine. Although we did not test the air, we surmised the ambient air contained traces of strontium from combustion of coal. Strontium was not detected in product water while testing several machines in western Canada where electricity is from hydro-electric sources. Volatile organic compounds (VOCs) in the entering air can also pass through the system into the product water unless one or more VOC filters are added to the water flow path. Particulates in the ambient air can be removed by air filters before the air enters the water-from-air processing system. Sediment filters can be inserted into the water flow path to remove fine particulates not removed by the air filter. Before starting long-term use of water-from-air product water at a site, it is wise to have a sample of the product water tested by a reputable laboratory to ensure the water quality meets national or World Health Organization water quality guidelines. Tests should be scheduled annually to verify that water quality remains acceptable.
Would the quantity of water produced vary on a day to day basis?
Yes, water production rate depends on the water vapour density ("absolute humidity") of the ambient air. The water vapour density changes according to weather conditions related to characteristics of the air masses passing through the region in which the water-from-air machine is located. Day-to-day variability is minor usually but month-to-month and seasonal variability can be substantial, especially in temperate climates.
Given the fact that water quality is affected by air quality, how then would one market this product in a third world country? Would any one manufacturer need to do air quality analyses in each interested market (country) before soliciting its business? Thank you. A concerned distributor.
The manufacturer and its distributors should be aware of air quality conditions in each market area. Air quality could be different in the same city. The city's suburbs are likely to have better air quality than its industrial areas. Alternatively, prevailing winds may keep industrial or zones with heavy vehicle traffic relatively unpolluted while suburbs downwind are enveloped in polluted air. Ultimately,it is more effective to test water quality than air quality—it is the end result that counts. A responsible distributor of water-from-air machines (perhaps sharing costs with the manufacturer) should do an annual test of the water from at least one representative machine from each "air-shed" of their market area. This comprehensive test should include inorganic parameters, organic parameters, and physical parameters. Testing should also be done for microbes. If nuclear power plants are nearby, it would be wise for the testing to include radio-logical parameters. Although this type of water testing is expensive, a proportion could be factored into the selling price of the machines at both the manufacturer's and distributor's levels, or into maintenance contracts, so that there is no financial-based excuse for not performing the annual tests. The end-users should not be expected to do the testing. The manufacturer and distributor must bear the responsibility as part of their role as water-from-air technology providers in their region. If problems with the water quality are found, the end-users must be notified immediately. Therefore, best efforts must be made to maintain up-to-date lists of machine owners—just as automobile dealers and manufacturers keep track of customers in case there has to be a recall for defective vehicles. Specific filters, such as for volatile organic compounds (VOCs) may have to be added to machines in some market areas. Although all this may come across as discouraging, keep in mind that many regions where water-from-air machines are practical are likely to have relatively clean air. The increasing need to use water-from-air machines is yet another reason for all people to treat our "atmospheric-commons" with respect and not use the atmosphere as a dumping place for waste products of our activities.
How much energy is used to produce a liter of water in optimal conditions?
First let us say that optimal conditions = standard test conditions for dehumidifiers which is 26.7 C dry bulb air temperature, relative humidity 60%, and air pressure at one atmosphere. Under these test conditions, I have found both through modeling and real world measurement experience that 20 L/day machines consume 0.68 kWh per litre of water produced. Larger machines, typically rated at 2500 L/day consume 0.4 kWh per litre of product water. This is because the larger machines are more efficient at using the atmosphere as a heat sink. It is interesting to note that in natural systems, the energy consumed to change the phase of water from gas to liquid (enthalpy of vaporization, formery called 'latent heat') is 0.681 kWh per litre.
Is there a solar pv component to provide energy to the WFA device?
At this time, the cost of solar PV systems remains too high to be feasible to use with water-from-air systems. Sufficient battery storage must be part of the system to allow 24 hour operation. Every hour of operation is precious because of the relatively low rate at which water-from-air systems process water vapour into liquid water.
Are these products/devices currently being produced and distributed?
Several manufacturers are producing and distributing water-from-air systems at various scales. I have compiled a list of links to manufacturers. Caveat emptor.
I am wondering if it is a practical idea to use the water from my AC to refurbish the water in my Aquaponic pool. Because my city water I am using is treated with that Cloramine, and I live down the street from the tower. So I am sure I get one of the initial doses. I drink bottled water, and that Cloramine just doesn't die overnight. So to fill my tank it takes a least a week. Is it cool to use it because I have Talipia and the ones it doesn't kill most likely well be eaten ? The humidity in Central Florida is excessive. So the AC pours out water and this would be an excellent way to use it. Is it coated with Heavy metal from the AC or what ?
Although the water from the air conditioner will contain some bacteria and some metal ions from the evaporator coil and other surfaces in the AC unit, these should normally be in such small concentrations that the water should be fine for the fish, especially on an occasional use basis.
If you are going to use the AC water for aquaponics for the long-term I recommend investing the time and money to get the water tested for bacteria and metal content. Some results may be higher than the guidelines for human consumption but then you need to make a judgement call (based on the chloramine treated alternative and other options) whether or not to provide the AC water to your fish. Testing should be repeated at least annually. The air conditioner's air filter and interior surfaces contacting air or water should be cleaned at least monthly.
Disclaimer: The entire risk of the use of any information in this message is assumed by the user.
Although the water from the air conditioner will contain some bacteria and some metal ions from the evaporator coil and other surfaces in the AC unit, these should normally be in such small concentrations that the water should be fine for the fish, especially on an occasional use basis.
If you are going to use the AC water for aquaponics for the long-term I recommend investing the time and money to get the water tested for bacteria and metal content. Some results may be higher than the guidelines for human consumption but then you need to make a judgement call (based on the chloramine treated alternative and other options) whether or not to provide the AC water to your fish. Testing should be repeated at least annually. The air conditioner's air filter and interior surfaces contacting air or water should be cleaned at least monthly.
Disclaimer: The entire risk of the use of any information in this message is assumed by the user.
In which industry fields are atmospheric [water generators] distributed? I heard about military-, agriculture- and humanitarian applications. But are there no[t] any other industries that might be interested in this innovative technology?
Below is a list of industries that have either contacted my companies (Atmoswater Research; Canadian Dew Technologies Inc.) for information or are specifically addressed by various manufacturers in their marketing materials. Year-round water production is possible only in tropical latitudes (between 30° N and S near sea level). Atmospheric water generators (AWGs) can be a cost-effective technological core for small to medium enterprises needing a reliable source of fresh water in locations with water scarcity. Candidate enterprises, other than those mentioned in your question, include:
Below is a list of industries that have either contacted my companies (Atmoswater Research; Canadian Dew Technologies Inc.) for information or are specifically addressed by various manufacturers in their marketing materials. Year-round water production is possible only in tropical latitudes (between 30° N and S near sea level). Atmospheric water generators (AWGs) can be a cost-effective technological core for small to medium enterprises needing a reliable source of fresh water in locations with water scarcity. Candidate enterprises, other than those mentioned in your question, include:
- Beverage manufacturing (bottled water, juices, soft drinks, breweries, distillers)
- Food processing
- Textile production
- Hotels & resorts
- Hospitals (feed-water for dialysis machines)
- Industrial camps (oil & gas, mining)
Do you have any information on building your own water from air machine using a Peltier tec cooler? I thought it might work out on my sailboat with uses of my solar power; would I have to worry about salt?; could it be transferred through the air?; I would store the water in tank for bathing; the water for drinking I would filter , what are your thoughts?
Although I have experimented with thermo-electric devices to condense water from the air, I have not made enough progress to compile information for others to follow as do-it-yourself atmospheric water generator project.
Thermo-electric chillers coupled with solar PV is an appealing combination but the present relatively low efficiency of both technologies is a challenge for making a practical water production system.
In a marine environment, there may be some salt appearing in the condensate but my intuition is that it would be a much lower concentration than reverse osmosis product water which can contain up to 300 ppm dissolved solids (salt). Any water that is stored for drinking should be filtered and treated with UV or chlorination before consuming. Or, it could simply be boiled just before drinking it. Drinking water supply systems should have the water quality tested before being put into use and should then be re-tested annually.
Using any water-from-air method for producing bathing (showering) water is unlikely to be be cost effective. I would recommend that the water-from-air product water (with its high energy cost) be used exclusively for drinking and cooking.
Although I have experimented with thermo-electric devices to condense water from the air, I have not made enough progress to compile information for others to follow as do-it-yourself atmospheric water generator project.
Thermo-electric chillers coupled with solar PV is an appealing combination but the present relatively low efficiency of both technologies is a challenge for making a practical water production system.
In a marine environment, there may be some salt appearing in the condensate but my intuition is that it would be a much lower concentration than reverse osmosis product water which can contain up to 300 ppm dissolved solids (salt). Any water that is stored for drinking should be filtered and treated with UV or chlorination before consuming. Or, it could simply be boiled just before drinking it. Drinking water supply systems should have the water quality tested before being put into use and should then be re-tested annually.
Using any water-from-air method for producing bathing (showering) water is unlikely to be be cost effective. I would recommend that the water-from-air product water (with its high energy cost) be used exclusively for drinking and cooking.
"Does generating water from air have negative effects on soil or plants? Seems like you are taking water that can supply moisture to plants away as well as causing increased soil erosion." - Greg G., 2022-09-08
A recent analysis indicates that even if millions of atmospheric water generators were used worldwide they would have a negligible effect on the concentration of water in the atmosphere. See https://www.atmoswater.com/atmoswater-blog-by-roland-wahlgren/impact-on-the-atmospheric-water-reservoir-from-using-water-from-air-systems-an-update
Local soil erosion could be a problem if, after the water from air is used for whatever purpose, it is dumped on the ground in an uncontrolled manner. Wastewater disposal should use established best plumbing practices.
A recent analysis indicates that even if millions of atmospheric water generators were used worldwide they would have a negligible effect on the concentration of water in the atmosphere. See https://www.atmoswater.com/atmoswater-blog-by-roland-wahlgren/impact-on-the-atmospheric-water-reservoir-from-using-water-from-air-systems-an-update
Local soil erosion could be a problem if, after the water from air is used for whatever purpose, it is dumped on the ground in an uncontrolled manner. Wastewater disposal should use established best plumbing practices.
"What do you think of using adsorption based processes as compared to [refrigeration] based processes [in water-from-air systems]?" - J. S., 2022-10-27
Adsorption versus refrigeration-based processes:
Advantages of adsorption processes for water-from-air:
Adsorption versus refrigeration-based processes:
- Read what Global Water Intelligence wrote - link via blog post at https://www.atmoswater.com/atmoswater-blog-by-roland-wahlgren/status-of-the-water-from-air-industry-in-2021-from-the-viewpoint-of-global-water-intelligence
- Scroll down to last question ("Mojave desert...") in my blog post https://www.atmoswater.com/atmoswater-blog-by-roland-wahlgren/my-answers-to-questions-asked-in-oct-20-2020-webinar-introduction-to-atmospheric-water
Advantages of adsorption processes for water-from-air:
- can be integrated with solar thermal energy systems or low-grade (waste) heat sources so can be economical to use off-grid
- can be used in outdoor air with relatively low relative humidity coupled with low dew-points
- academic peer-reviewed research is creating a rapidly expanding knowledge-base (see relevant publications listed at https://www.atmoswater.com/articles-about-water-from-air.html)
- capital cost usually lower than equivalent capacity refrigerated system
- Avoids use of refrigerants with their associated environmental hazards
- apparently difficult to commercialize---to my knowledge the only two commercial products at this time are by Drupps AB and SOURCE Global, PBC (links at https://www.atmoswater.com/manufacturers-and-suppliers-of-atmospheric-water-generators--water-from-air-machines.html)---readers with up-to-date information about other commercialized systems please contact me. Thanks.
- relatively high operating cost (energy cost) if use grid electricity to operate
- off-grid operation dependent on variability of solar energy resource or siting near a waste energy source
- huge knowledge-base and wealth of operational experiences
- commercialization of water-from-air systems well advanced; many choices for buyers
- site requirements more flexible than for adsorption systems
- relatively high capital and operating costs
- not yet economical to use with solar photovoltaic energy systems; needs power from grid, wind, or diesel generators
- Usually use hazardous refrigerants
- Relative humidity of entering air must be above approximately 40% and dew-point should be above about 5 °C to avoid freeze-up of the evaporator coil (the chilled coil)
Water pseudo-science: Curious about terminology used at some water-from-air system provider's websites like "Pi Water", "Alkaline Water", and so on? Visit the excellent website by retired chemistry professor Stephen Lower (Vancouver, Canada). I also recommend reading an interesting article by Jack Barber, titled pH paranoia: Understanding alkaline water claims (March 2012 issue of Water Technology). The take-home message was there is no health benefit to alkaline water. In fact, "...once alkaline water enters your stomach, your body simply pours in greater amounts of [gastric] acid to neutralize it."