Water from air basics
Absolute humidity is the actual amount of water vapor in a given amount of air; the humidity ratio expresses it as grams of water per kilogram of dry air (g/kg). Engineers also call this figure the mixing ratio; the three terms are used almost interchangeably in water-from-air work. Unlike relative humidity, it doesn't shift when the air warms or cools.
This is the figure that decides how much water a machine can pull from the air. The WaHa Vaporator® holds rated output down to 1 gram of water per kilogram of air, which is why it keeps working in places where condensing machines stall. See operating envelope.
Atmospheric water generation is the process of extracting water vapor from the air and turning it into liquid water that people can drink or use. The term covers every method, including cooling air until moisture condenses and capturing moisture with a desiccant.
AWG makes water where the air is, so a site doesn't need a pipeline, a well or a delivery truck. How well it works depends on the method and on how dry the local air gets. See compressor-based AWG and desiccant.
An atmospheric water generator is a machine that produces liquid water from the moisture in the surrounding air. Most units on the market cool air below its dew point so water condenses; others use a desiccant to capture moisture first.
WaHa's machines are atmospheric water generators built on the WaHa Vaporator® engine. In water mode they're sold as the Oasis series.
Atmospheric water harvesting is the term researchers and standards bodies use for the same thing as atmospheric water generation: taking water vapor out of the air and turning it into liquid water. Industry mostly says AWG; universities and the International Atmospheric Water Harvesting Association (IAWHA) say AWH.
The two terms are interchangeable. WaHa uses AWG on this site and AWH when working with researchers. See atmospheric water generation.
The atmospheric water reservoir is the total water vapor held in the air at any moment, about 12,900 trillion liters (NASA/USGS). The hydrological cycle turns that stock over roughly 40 times a year (NASA).
For scale: if every person on earth ran a machine producing 5 liters a day, the total would be 41 billion liters a day, about 0.00032% of what the atmosphere holds, taken from a stock that refills continuously. Making water from air does not deplete the resource or change the weather. See hydrological cycle.
Condensation is the change of water from vapor to liquid, which happens when humid air meets a surface colder than its dew point. It's the same effect that fogs a cold glass on a hot day.
Condensation is the last step in almost every AWG. What differs between technologies is how they get the air ready for it.
The dew point is the temperature at which air becomes saturated and water vapor starts condensing into liquid. The lower the dew point, the drier the air.
Condensing AWGs have to chill air below its dew point to make water. In dry climates the dew point can sit below freezing, and at that point the coil frosts over instead of dripping. In dehumidification, the dew point is also how dry rooms are specified. See low dew point.
Dry-bulb temperature is the ordinary air temperature a thermometer reads; wet-bulb temperature is the lower reading from a thermometer whose bulb is kept wet, cooled by evaporation. The drier the air, the bigger the gap between the two.
Together with pressure, the two readings fix every other property of the air, which is why psychrometric charts are built around them. See psychrometrics.
The hydrological cycle is the continuous movement of water between the oceans, the atmosphere and the land, by evaporation, transport as vapor, precipitation and runoff. It is what keeps the air's water supply replenished.
About 503,000 cubic kilometers evaporate from the oceans each year and about 458,000 fall back as rain and snow, leaving roughly 45,000 to travel over land. Over land, evapotranspiration from soil and plants adds another 65,000, and about 45,000 returns to the sea as river runoff and groundwater flow (UNESCO, after Shiklomanov). A machine making water from air takes from a flow that is already in motion. See water vapor.
Latent load is the part of a building's or process's cooling load that comes from removing moisture, as opposed to lowering temperature. Removing moisture takes energy even when the temperature doesn't change.
In humid spaces, cold rooms and dry rooms, latent load can drive a large share of HVAC energy. Handling moisture separately, with a desiccant system, lets the cooling equipment work on temperature alone. See sensible load.
Psychrometrics is the study of the physical and thermal properties of moist air, such as its temperature, moisture content and heat content, and of how they change together. Engineers use a psychrometric chart to see how air will behave as it's heated, cooled, humidified or dried.
Every water-from-air and dehumidification design starts from psychrometrics, because it shows how much water the air holds and how much energy it takes to get it out.
Relative humidity is the amount of water vapor in the air, expressed as a percentage of the most the air could hold at the same temperature. At 100% RH the air is saturated; at 10% RH it holds a tenth of its maximum.
RH is the number on most weather apps, but it changes with temperature even when the actual amount of water stays the same. For sizing an AWG or a dehumidifier, engineers usually care more about absolute humidity.
Water vapor is water in its gas form, mixed invisibly into the air around us. Even air that feels dry carries some of it.
Every AWG system draws on the vapor the air already holds, a very large stock that the weather keeps refilling. See atmospheric water reservoir.
Back to top
How the technology works
Adsorption is the capture of molecules on the surfaces and inside the pores of a solid, held by weak physical forces rather than a chemical reaction. Absorption, by contrast, takes a substance into the bulk of a liquid or solid, the way a sponge takes up water.
Solid desiccants, including the MOF in the WaHa Vaporator®, adsorb water: they capture water molecules in their pores. The binding is more like a magnet than glue, which is why a modest amount of heat releases the water again. See desiccant regeneration.
An adsorption isotherm is the curve showing how much water a sorbent holds at each level of relative humidity, at a fixed temperature. It is the single most useful picture of what a desiccant will do.
Silica gel's curve climbs gradually, so it picks up water across a wide range but never fills quickly. A water-harvesting MOF's curve is a step: almost no uptake below a certain humidity, then nearly full load just above it. The step is what makes the material efficient, because the whole load is taken up and released over a narrow range rather than smeared across the curve. Where the step sits is a design choice, matched to the humidity at the site. See hydrophilic and hydrophobic.
Published water isotherms make the difference plain. Silica gel RD rises steadily from low humidity with no sharp transition. MOF-303 and MIL-160 take up most of their load below 20% relative humidity; SAPO-34 below 10%; Basolite A520 and CAU-10 step later, in the 20 to 40% range. A material with an early step works in drier air; one with a later step costs less heat to regenerate.
An angstrom is one ten-billionth of a meter, the unit chemists use for the size of atoms and molecules. A water molecule is about 2.7 angstroms across. A human hair is roughly 800,000.
MOF pore openings are measured in single-digit angstroms, which is why pore size alone decides what can enter and what cannot. See molecular selectivity.
The coefficient of performance is the ratio of heat delivered to electricity consumed. A resistance heater has a COP of 1; a heat pump delivers several units of heat per unit of electricity, so its COP is well above 1.
Legacy desiccant dehumidifiers regenerate with a gas burner or a resistance heater and get no COP advantage at all. The WaHa Vaporator® gains in three ways that compound: a thermodynamic engine with heat pump COP; regeneration at a low temperature, which takes less heat to release the water; and recovery of the latent heat of condensation back into regeneration. Together these are the 70 to 90 percent energy saving against silica gel wheel-based dehumidifiers. See inexpensive dry air.
Compressor-based AWG uses a refrigeration cycle to cool air below its dew point so water condenses on a cold coil. It's also called mechanical vapor compression (MVC), and it's the most common AWG design on the market.
It works well in warm, humid air and loses output as the air dries: output falls below rated at about 15 grams of water per kilogram of air and stops at about 8 g/kg. For comparison, 30 °C (86 °F) at 60% RH is about 16 g/kg, and a 22 °C (72 °F) office at 50% RH is about 8 g/kg. See derating and single-point rating. Under the AWG Viability Standard, compressor-based AWG covers 7.0% of global land and 1.0% of water-stressed land. See Where It Works and the AWG Technology Platforms Comparison.
There is a water quality consequence as well. A condensing machine makes water by chilling the open air stream until moisture forms on a coil, so the water and the air meet in the same place, and what the air carries can end up in the water. Dust, smoke, pollutants and soluble gases all arrive with the air. These machines therefore depend on filtration, typically air filters ahead of the coil and carbon, sediment and sometimes membrane stages after it, to bring the water to drinking quality.
Cycling stability is how well a sorbent holds its capacity through repeated loading and unloading, cycle after cycle, year after year. A material that performs well on its first cycle and fades is no use in equipment meant to run for a decade.
It is one of the practical reasons a water-harvesting MOF is chosen over a laboratory material with higher peak capacity. See uptime.
Derating is the drop in a machine's output below its rated figure as conditions move away from the point at which it was rated. For an atmospheric water generator, the condition that matters most is how much water the air holds, in grams per kilogram.
Compressor-based AWG begins derating at about 15 g/kg and stops producing at about 8 g/kg. The WaHa Vaporator® holds rated output down to 1 g/kg. The AWG Viability Standard measures derating across a full four-year climate record rather than at one condition. See single-point rating and Where It Works.
A desiccant is a sorbent whose job is water vapor: it takes moisture out of the air and holds it until something drives it back out. Silica gel, the packets shipped in shoe boxes, is the one most people have seen; zeolites and MOFs are the industrial ones. Desiccants dry air without chilling it, which is what makes them the standard answer for very dry spaces.
The material is later heated to release the captured water, a step called regeneration. Desiccants differ in how tightly they hold water and in how selective they are about what else they will hold, which sets both how dry they can drive the air and how much heat regeneration takes. See sorbent and metal-organic framework.
Desiccant regeneration is the step that drives captured water back out of a desiccant, usually with heat, so the material can absorb again. It's where most of the energy in a desiccant system goes.
How much heat regeneration needs, and where that heat comes from, is the main difference between one desiccant system and another. The WaHa Vaporator® handles regeneration inside its thermodynamic engine.
A desiccant wheel is a slowly rotating wheel coated with desiccant that picks up moisture from one airstream and releases it into another. One side of the wheel dries air; the other side is regenerated.
Wheels are the standard format in industrial dehumidification. In the WaHa Vaporator®, the desiccant wheel is matched to the site's humidity profile.
Heat of adsorption is the heat a desiccant releases as it takes up water vapor, roughly the heat the vapor gave up when it evaporated plus a little extra from binding to the material. Every solid desiccant releases it, and it warms the process air passing over the wheel.
In a conventional desiccant dehumidifier that warmth goes into the room and the building's cooling pays to remove it. In the WaHa Vaporator®, a patented passive air-to-air heat exchanger downstream sheds the adsorption heat toward ambient, and an optional indirect evaporative cooling stage, run on the machine's own harvested water, can take out more. The exchanger cannot cool below ambient, so where the target condition plus adsorption heat is already cooler than the surroundings it removes only part of the warmth. See sensible load.
Sorbents differ in how much extra energy that binding costs. Written as an equation, the heat of adsorption is the latent heat of vaporization of water, which is the same whatever the sorbent, plus a sorbent-specific amount on top. The smaller that extra amount, the lower the temperature needed to drive the water back out, and the better the efficiency of the whole machine. Measured as the extra energy beyond water's own latent heat, aluminum-based MOFs sit at roughly 10%, SAPO-34 around 15%, silica gel around 18%, and zeolite 13X around 31%. The ranges overlap at the edges, so the fair statement is that a MOF's excess is roughly half silica gel's, not a settled multiple.
A heat pump moves heat from one place to another using a refrigerant cycle, delivering several units of heat for each unit of electricity it consumes. A refrigerator, an air conditioner and a heat pump clothes dryer all work this way.
The thermodynamic engine inside the WaHa Vaporator® is a sealed, closed-loop heat pump architecture protected by WaHa's foundational patents. It supplies the heat that regenerates the desiccant instead of buying that heat from a gas burner or resistance heater. See thermodynamic engine and coefficient of performance.
Hydrophilic means water-attracting; hydrophobic means water-repelling. For a desiccant it is a matter of degree: how readily the material pulls water out of air, and how tightly it holds it once it has it.
The more hydrophilic a sorbent, the drier the air it can still take water from, and the more heat it takes to get that water back out. The more hydrophobic, the less water per day and the cheaper each liter. Neither is simply better, which is why the sorbent is chosen against the humidity the site actually sees. See adsorption isotherm and operating envelope.
Latent heat of condensation is the heat water vapor gives up when it turns back into liquid; it equals the heat the water absorbed when it evaporated. For every liter of water condensed, that is a large, fixed amount of heat.
In most machines that heat is thrown away. The WaHa Vaporator® recovers the latent heat of condensation inside its sealed chamber and returns it to the desorption loop, where it helps release the next charge of water from the desiccant. See thermodynamic engine.
Mechanical vapor compression is the ordinary refrigeration cycle: a compressor raises a refrigerant's pressure and temperature so it can shed heat, then the refrigerant expands and gets cold enough to chill a coil. Air conditioners, refrigerators and condensing dehumidifiers all run on it.
In water-from-air work, MVC describes machines that make water by chilling air below its dew point. In dehumidification, the same cycle drives a condensing dehumidifier, which collects water in a tank rather than venting it. See compressor-based AWG.
A metal-organic framework is a crystalline material built from metal clusters joined by organic linkers, forming a highly porous structure with a very large internal surface area. MOFs can be designed at the molecular level to capture specific molecules, including water.
WaHa's technology is built on the MOF chemistry awarded the 2025 Nobel Prize in Chemistry. The WaHa Vaporator® uses a novel solid desiccant: a MOF.
A MOF works as a molecular separator. Its pores are built to a chosen size and chemistry, so the material takes up one kind of molecule and leaves the rest of the stream behind. That works in air and in liquids: MOFs are used to pull pollutants out of wastewater and to separate one hydrocarbon from another. Water-harvesting MOFs are built to prefer water. See molecular selectivity.
What makes MOFs useful here is the combination rather than any single property: high water capacity, low heat to release the water, fast loading and unloading, and stable performance over many cycles. They are also tunable. Because the pore size and chemistry are design choices, the humidity at which the material takes up and releases its water can be set to match the climate the machine will work in. A more water-attracting framework makes more water per day at a higher energy cost; a more water-repelling one makes less at a lower cost; the choice is made per site. See adsorption isotherm and hydrophilic and hydrophobic.
Molecular selectivity is a porous material's ability to take up one kind of molecule out of a mixture and leave everything else behind. Two things produce it: the size of the pore openings, which decides what can get in at all, and how strongly the framework holds each molecule that fits.
The pores in a water-harvesting MOF are a few angstroms across, roughly the width of a few atoms. Large molecules, including most of the volatile organic compounds in smoke and smog, and anything carried as a particle, cannot get in and pass straight by. Among the small molecules that can get in, water wins: the framework binds water far more strongly than it binds the others, so an arriving water molecule displaces whatever is sitting in the pore. When the MOF is heated, what comes back off is water.
In the WaHa Vaporator® that vapor condenses inside a sealed chamber rather than in the open air stream, so the water is not re-exposed to the surroundings on its way to the tank. The practical result is that the machine can run through wildfire smoke in Colorado or California, or in the polluted air of a large city, and the air outside is not what ends up in the water. See adsorption and volatile organic compounds.
Reticular chemistry is the field of linking molecular building blocks with strong bonds into ordered, extended frameworks, such as metal-organic frameworks. It lets chemists design porous materials with a chosen pore size and function.
WaHa was co-founded in 2018 by Professor Omar Yaghi of UC Berkeley, the inventor of reticular chemistry and of metal-organic frameworks (MOFs). In October 2025, that work was honored with the Nobel Prize in Chemistry. WaHa holds the exclusive license to three water-harvesting MOF patent families from Professor Yaghi's UC Berkeley laboratory. See Patents.
A single-point rating states a machine's output at one set of conditions, usually the most favorable the maker could pick; in plain language, a best-day rating. Most atmospheric water generators are rated at about 30 °C (86 °F) and 60% relative humidity, which is roughly 16 grams of water per kilogram of air.
That condition is the best point on the machine's curve, not a promise of daily supply. The useful question is how often a site's air meets the condition the machine needs, which is what the AWG Viability Standard and the Climate Viability Explorer answer. See derating and rated output.
Solid desiccants capture water on the surface of a porous material, while liquid desiccants absorb water into a salt solution. Both dry air, but they're handled very differently.
Liquid desiccant systems circulate a brine that has to be managed and contained. Solid desiccants stay in place, usually on a rotating wheel. WaHa uses a solid desiccant. Both are sorption systems, so in both cases it is water vapor rather than the air stream that moves on to be condensed. The difference is what else is in the system: a liquid desiccant circulates a salt solution that has to be contained, while a solid desiccant stays fixed in place.
A sorbent is any material that takes another substance up, either onto its surfaces and into its pores (adsorption) or into its bulk (absorption). It is the general word; adsorbent and absorbent are the two specific ones.
Every desiccant is a sorbent, but sorbents do many other jobs: capturing carbon dioxide, drying solvents, cleaning up spills. In water-from-air work the sorbent is whichever material does the capturing, and the choice of sorbent sets how dry the air can get and how much heat it takes to release the water again. See desiccant and adsorption.
Sorption-based AWG uses a desiccant to capture water vapor from the air, then heat to release that vapor into a small sealed volume where it condenses. The desiccant concentrates the moisture before condensation, so the machine does not have to chill a large volume of air.
That is why sorption machines keep working in air far too dry for a compressor-based unit. The WaHa Vaporator® is sorption-based, using a MOF desiccant wheel and a thermodynamic engine for regeneration. Under the AWG Viability Standard, it covers 70.5% of global land. See AWG Technology Platforms Comparison.
The water never forms in the open air stream. The sorbent takes up water molecules and leaves the rest of the air behind, then releases them inside a separate chamber where they condense. Air and water are kept apart by the architecture rather than cleaned up afterward, which is why a sorption machine does not depend on a stack of filters to reach drinking quality. See molecular selectivity.
In WaHa's usage, the thermodynamic engine is the sealed, closed-loop system inside the WaHa Vaporator® that moves heat to regenerate the desiccant and condense the water. It is a heat pump architecture protected by WaHa's foundational patents.
Because it moves and reuses heat inside the loop instead of buying it from a burner or resistance heater, it is central to how the WaHa Vaporator® keeps energy use down. See heat pump, coefficient of performance, and The WaHa Vaporator® Engine.
The WaHa Vaporator® is WaHa's patented platform that combines a MOF-based desiccant wheel with a sealed thermodynamic engine to make water from air or to produce inexpensive dry air. The same platform runs in either water mode or dehumidifier mode.
It operates from -20 to 55 °C (-4 to 131 °F) and at humidity as low as 10% RH. It is one platform, configured for the site. See operating envelope and The WaHa Vaporator® Engine.
Water uptake capacity is how much water a sorbent holds when fully loaded, given as grams of water per gram of sorbent or as a percentage of its own weight. Together with how fast it loads and unloads, it sets how much sorbent a machine needs.
Capacity alone does not decide the design. A material that holds a lot but needs high heat to release it can cost more per liter than one that holds less and lets go easily. See adsorption isotherm and heat of adsorption.
Back to top
Dehumidification
A controlled humidity space is a room or facility where relative humidity is held within a set band to protect products, processes or materials. Pharmaceutical packaging, powdered food lines, archives and electronics assembly are all common examples.
These spaces usually sit at ordinary room temperature, so the whole job is moisture removal, which suits desiccant dehumidification well.
Dehumidification is the removal of water vapor from air to reach a target humidity or dew point. It protects products, processes and buildings from moisture damage.
Most commercial dehumidifiers either chill air to condense moisture out or pass it over a desiccant. Chilling gets less effective as the target gets drier, so dry spaces usually rely on desiccants. Desiccant dehumidifiers normally need an exhaust duct for the reactivation air; the WaHa Vaporator® does not, because its moisture leaves as liquid water. See process air and reactivation air.
Desiccant dehumidification dries air by passing it over a material that takes the moisture up, rather than by chilling the air until moisture condenses out. It is the method used wherever air has to be drier than a cold coil can practically make it.
A conventional desiccant dehumidifier regenerates its wheel with a gas burner or an electric resistance heater and vents the moist reactivation air outdoors. The WaHa Vaporator® is a desiccant dehumidifier too, but it regenerates with a thermodynamic engine and condenses the moisture to liquid inside a sealed chamber, so it needs no exhaust and uses far less energy. See silica gel wheel dehumidifier and coefficient of performance.
Frost and ice buildup in cold storage happens when moist air enters a refrigerated space and freezes onto evaporator coils, floors and product. It forces defrost cycles, cuts cooling efficiency and creates slip hazards.
Drying the air before it reaches the cold zone stops the problem at the source. See Cold Storage Dehumidification.
The frost point is the temperature at which water vapor turns straight into ice on a surface; below 0 °C (32 °F) it takes the place of the dew point. The two differ by a degree or two at the same moisture content.
Dry rooms are usually specified by dew point even when the figure is below freezing, so a "-40 °C (-40 °F) dew point" is strictly a frost point. The convention is harmless as long as everyone involved uses the same term. See low dew point and dry rooms.
Grains per pound is the US customary unit for humidity ratio: grains of water vapor per pound of dry air, where 7,000 grains make one pound. It is the unit on most US dehumidifier catalogs and HVAC specifications.
To convert, multiply grams per kilogram by 7: 1 g/kg is 7 gr/lb, so the WaHa Vaporator® rated floor of 1 g/kg is 7 gr/lb. See absolute humidity, humidity ratio and mixing ratio.
Inexpensive dry air is WaHa's term for the dehumidified process air produced by the WaHa Vaporator® in dehumidifier mode, with far less energy than conventional desiccant systems. The WaHa Vaporator® uses 70 to 90 percent less energy than silica gel wheel-based dehumidifiers.
It's aimed at facilities where drying air is a large, constant operating cost, such as cold storage and battery dry rooms. See Inexpensive Dry Air.
Low dew point dehumidification delivers air so dry that its dew point sits well below freezing; a dry room is an enclosed production space held at that condition. Dry rooms are specified by dew point, since relative humidity readings get unreliable at such low moisture levels.
Lithium-ion battery cells, semiconductors and some pharmaceuticals are made in dry rooms, because trace moisture ruins the product. Keeping a large room that dry around the clock is one of the biggest energy loads in those plants.
Process air is the airstream a desiccant dehumidifier dries and delivers to the space; reactivation air is the separate airstream that carries moisture away from the desiccant during regeneration. The two streams pass through different sections of the wheel.
A silica gel desiccant dehumidifier runs both streams, so it needs an exhaust duct to vent the moist reactivation air outdoors. The WaHa Vaporator® has no reactivation air stream and no exhaust: regeneration happens inside a sealed chamber and the moisture leaves as liquid water. That is why the machine can be wheeled into a room and switched on, with no ductwork or wall penetration to design, permit or pay for. It can be ducted if a site wants. Dehumidifiers are rated by moisture removed and, for industrial desiccant units, by process airflow; WaHa's V-series model numbers give the airflow in cubic meters per hour. See V-series.
Sensible load is the part of a cooling load that comes from lowering the air's temperature, as opposed to removing its moisture. Latent load is the moisture part; the two together make up the total load.
A desiccant dehumidifier takes on the latent load but adds a little sensible load through heat of adsorption. The WaHa Vaporator® sheds that heat with a passive air-to-air exchanger and, where wanted, indirect evaporative cooling. See heat of adsorption and latent load.
A silica gel wheel dehumidifier is a desiccant dehumidifier that uses a rotating wheel coated with silica gel to dry air, then regenerates the wheel with a hot airstream. It's the incumbent technology for industrial low-humidity spaces.
Regenerating silica gel takes a lot of heat, which makes these units expensive to run. The WaHa Vaporator® regenerates its wheel with far less energy; see inexpensive dry air and coefficient of performance. See also silica gel.
Back to top
Water quality
Distilled-grade water is water with a purity comparable to distilled water, containing little to no dissolved minerals, salts or contaminants.
Water made from air starts out this way because of what gets in. In a MOF-based machine the sorbent takes up water and leaves the rest of the air stream behind, and the water is released and condensed inside a sealed engine, so the finished water does not carry what the outside air was carrying. WaHa will publish full laboratory results for its commercial machines once that testing is complete. Minerals can be added back for taste. See molecular selectivity and remineralization.
Drinking water standards are the legal limits set by regulators for contaminants in water intended for people to drink. Examples include the US EPA National Primary Drinking Water Regulations, the WHO Guidelines for Drinking-water Quality and the UAE's UAE.S 149.
WaHa tests its water against the standard that applies where the machine is installed and will publish the results for its commercial machines. NSF, UL and CE certifications are in progress.
Microplastics are plastic particles smaller than 5 millimeters that come from the breakdown of larger plastic items and from products like synthetic textiles. They've been found in tap water, bottled water and the air.
Making water from vapor leaves the particles behind, since only water molecules evaporate. Producing water on site also takes single-use bottles out of the supply chain.
NSF/ANSI 61 is the North American standard for materials and components that touch drinking water; it limits what those materials can leach into the water. It covers pipes, fittings, tanks, coatings and the parts of a water-making machine that the water passes through.
WaHa's commercial machines use a water path built to this standard. The pilot units behind WaHa's early water tests were built to prove the physics, not to NSF/ANSI 61, so their results are not a limit on the commercial product. See drinking water standards.
PFAS (per- and polyfluoroalkyl substances) are a large family of synthetic chemicals that resist breaking down and build up in water, soil and the body. They're often called "forever chemicals."
PFAS have been found in drinking water supplies around the world and are hard and costly to remove. Water made from vapor has no contaminated source to clean up in the first place; the air is the supply, and PFAS in air is negligible compared with PFAS in surface and ground water.
Remineralization is adding minerals, usually calcium and magnesium salts, back into very pure water to give it a familiar taste and a mild buffering capacity. It is routine for desalinated and distilled water.
Water condensed from vapor starts with almost no dissolved minerals, so many users add some back before drinking. The amount is a matter of taste and local preference. See total dissolved solids.
Total dissolved solids is the combined amount of minerals, salts, metals and other substances dissolved in water, usually measured in milligrams per liter or parts per million. It's a common quick measure of water purity and taste.
Condensed water starts with very low TDS. Some users add minerals back for taste or for a specific process. See remineralization.
UV disinfection uses ultraviolet light to inactivate bacteria, viruses and other microorganisms in water without adding chemicals. It's widely used in municipal and point-of-use treatment.
A UV lamp is one of the three consumables in a WaHa machine, alongside air filters and water filters. See total cost of ownership.
Volatile organic compounds are carbon-based chemicals that evaporate easily at ordinary temperatures, so they move through the air rather than staying put. Solvents, fuels, paints, adhesives, cleaning products and wildfire smoke all release them, and many are regulated as health hazards.
VOC molecules are mostly larger than a water molecule, and the heavier ones cannot enter a water-harvesting MOF's pores at all. The smaller ones that can enter do not stay: the framework holds water far more strongly, so water takes the site. See molecular selectivity.
Back to top
Water supply and business models
Point-of-use water is water produced or treated at the place where it's consumed, instead of at a central plant and piped or shipped in. Decentralized water systems spread many small sources across sites.
Producing water where it's used removes the pipes, trucks and bottles in between. That matters most at remote sites and in places where the grid water is unreliable.
Total cost of ownership is the full cost of a system over its working life, including purchase, installation, energy, consumables, maintenance and downtime. It's a better basis for comparison than purchase price alone.
A WaHa machine has three consumables: air filters, water filters and a UV lamp. It's serviceable by any HVAC technician and uses no chemicals, no membranes and no brine. The carbon and sediment filters are there as a second line of defense rather than as the thing that makes the water clean, and the UV lamp protects water already made and sitting in storage, which is a different job from producing it.
Trucked water is water delivered to a site by tanker truck, usually because there's no piped supply or the local source isn't safe. It's common at remote camps, construction sites and off-grid facilities.
The water itself is the cheap part. Driver time, fuel, truck hire and the risk of a missed delivery are what add up. Making water on site takes those costs off the table.
Water resilience is the ability of a building, site or community to keep a reliable water supply through drought, supply cuts or infrastructure failures. It's usually built by adding a second, independent source.
Water from air adds a source that doesn't depend on rainfall, groundwater or a municipal main.
Water scarcity is a lack of enough available water, in quantity or quality, to meet the needs of people, farms and industry in an area. It can come from physical shortage or from a lack of infrastructure to deliver water that exists.
2.1 billion people lack safely managed drinking water (WHO/UNICEF 2025). Water scarcity threatens about 8% average global GDP loss by 2050 (Global Commission on the Economics of Water, 2024).
Water stress is the condition in which demand for water in a region takes up a large share of the renewable supply available. The World Resources Institute's Aqueduct tool is the most widely used way to measure it.
About 4.36 billion people live under water stress. Under the AWG Viability Standard, the WaHa Vaporator® serves 4.07 billion of them, or 93.4%, and covers 83.4% of water-stressed land. See Where It Works.
Water-as-a-service is a model in which a provider builds, owns and operates the water system on a customer's site and charges a fixed recurring fee, so the customer has no upfront capital cost. It's similar to how many companies now buy power or software.
WaHa can build, own and operate WaHa Vaporator® systems on this basis, scaling and moving them as a site's needs change.
Back to top
WaHa terms
The AWG Viability Standard is WaHa's utility-grade test of where an atmospheric water generator can be relied on: at least 90% of rated daily production on at least 90% of days. It was published in July 2026.
The analysis uses ERA5 climate data (2021 to 2024), WRI Aqueduct 4.0 and WorldPop 2020. By that standard, the WaHa Vaporator® covers 70.5% of global land, compared with 7.0% for compressor-based AWG. See Where It Works and the AWG Technology Platforms Comparison.
The Climate Viability Explorer is WaHa's free public tool that scores any location on earth for the share of days an atmospheric water generator would clear the AWG Viability Standard. It runs on four years of daily ERA5 climate data (2021 to 2024) and shows results for the WaHa Vaporator® and for compressor-based AWG side by side.
It also scores a whole list of sites at once, which is how a company with many facilities can see where water from air is a reliable supply. The method is published under an open license. See Where It Works.
An IP rating (ingress protection, IEC 60529) is a two-digit code for how well an enclosure keeps out solids and water; the first digit is solids, the second is water. IP65 means dust-tight and protected against water jets from any direction.
The Oasis-24 Outdoor is designed to IP65, so it can sit outside in dust and rain without a shelter. See Products.
Oasis is WaHa's line of atmospheric water generators, the WaHa Vaporator® running in water mode; the number in each model name is its rated output in liters per day. The rating holds across the operating envelope, not at a single best-day condition. An Oasis-24 is rated at 24 liters per day, and an Oasis-200 at 200.
See rated output and Products.
An operating envelope is the range of conditions, such as temperature and humidity, within which a machine delivers its rated performance. Outside the envelope, output drops or the machine shuts down.
The WaHa Vaporator® operates from -20 to 55 °C (-4 to 131 °F), at humidity as low as 10% RH, and holds rated output down to 1 gram of water per kilogram of air. The desiccant wheel is matched to the site's humidity profile, and sub-freezing installations add freeze protection for the water line.
A pilot test is a measured trial of a machine on a customer's site under the site's real conditions, before a full installation. The machine's telemetry records what it produced and what it used, day by day.
For dehumidification, a pilot usually runs the WaHa Vaporator® alongside the existing equipment, which stays in place as backup until the results are in. Contact WaHa to discuss a site evaluation. See Talk to WaHa.
Rated output, or nameplate, is the daily water production a manufacturer states for a machine. For most atmospheric water generators it applies only at the single condition the machine was rated at.
WaHa rates the Oasis series to hold its figure across the operating envelope, down to 1 gram of water per kilogram of air. See single-point rating and operating envelope.
Telemetry is the automatic logging and remote reporting of a machine's operating data. For a water-from-air machine that means inlet and outlet air conditions, energy use, run state and liters produced.
Every WaHa Vaporator® carries telemetry, which is how WaHa measures uptime and output at pilot sites and how a customer sees what the machine is doing without taking manual readings. See uptime.
Uptime is the share of time a system is running and available to do its job, usually given as a percentage. Utility and industrial buyers treat it as a core reliability measure.
WaHa has recorded 99.999% measured uptime across monitored pilot machines (UAE and Sweden). See Proven, Not Promised.
The V-series is the WaHa Vaporator® running in dehumidifier mode; the number in each model name is its process airflow in cubic meters per hour. The number is airflow, not water removed; a V-1000 moves 1,000 cubic meters of process air per hour. It delivers inexpensive dry air for industrial and commercial spaces.
See Products and process air.
A viable day is a day on which the local air lets an atmospheric water generator deliver at least 90% of its rated output. The AWG Viability Standard requires at least 90% of days in a four-year record to be viable before it calls a site reliably served.
Counting days rather than averaging output matters because drinking water has to arrive every day; a machine that makes double on good days cannot make up for days with nothing. See AWG Viability Standard.
Back to top
Sorbent materials
Aluminum fumarate is a water-stable metal-organic framework made from aluminum and fumaric acid, sold commercially by BASF as Basolite A520. It was the first MOF produced at industrial scale and at a price that let it be used in equipment rather than only in laboratories.
Its water uptake steps up in the region of 20 to 30 percent relative humidity, so it works well in moderately humid air and releases its water cheaply. It is also notable for surviving thousands of adsorption and desorption cycles without losing capacity. See cycling stability.
CAU-10 is an aluminum isophthalate metal-organic framework, named for the university where it was first made, Christian-Albrechts-Universität in Kiel. Its water uptake steps at roughly 15 to 20 percent relative humidity.
It is one of the most cycle-stable water sorbents on record, with published tests running to 10,000 adsorption and desorption cycles without measurable loss. See cycling stability.
MIL-160 is an aluminum furandicarboxylate metal-organic framework, built on the same structure as CAU-10 with a different organic linker. Swapping the linker makes it considerably more water-attracting: its uptake step falls at roughly 5 to 10 percent relative humidity.
That makes it the choice when air is very dry, and it is the reason the same framework family can be aimed at climates from humid to arid by changing one component. The trade is energy: a material that takes water from drier air needs more heat to give it back. See hydrophilic and hydrophobic.
MOF-303 is an aluminum-based metal-organic framework developed for water harvesting at Professor Omar Yaghi's laboratory at UC Berkeley. It takes up water in a sharp step at low relative humidity and gives it back at a low regeneration temperature.
It was the material behind the first demonstrations that water could be harvested from desert air with no power input beyond sunlight. See metal-organic framework.
SAPO-34 is a silicoaluminophosphate molecular sieve with pore openings of about 3.8 angstroms, built on the same framework pattern as the mineral chabazite. Engineers often call it a small-pore zeolite; chemists call it a zeotype, since true zeolites are aluminosilicates and SAPO-34 contains phosphorus.
It takes up water in a step at low humidity and regenerates at a moderate temperature, which is why Mitsubishi commercialized it as an adsorbent for heat pumps and chillers. Its binding energy sits between a MOF's and silica gel's. See adsorption isotherm.
Silica gel is a porous form of silicon dioxide, the oldest and most widely used industrial desiccant. It is the material in the small packets shipped with electronics and shoes, and in most desiccant dehumidification wheels in service today.
Its water uptake rises gradually across the humidity range rather than in a step, so it picks up moisture almost anywhere but never fills quickly, and it holds that moisture tightly enough that regeneration takes a lot of heat. Cheap, stable and well understood; its cost shows up in the energy bill rather than the purchase price. See adsorption isotherm.
Zeolite 13X is a synthetic crystalline aluminosilicate, a large-pore member of the zeolite family, used where air has to be driven extremely dry. It is a legacy industrial desiccant found in gas drying, air separation and deep-drying applications.
It is strongly water-attracting, which is both its use and its cost: it will pull moisture out of very dry air, and it needs regeneration temperatures in the hundreds of degrees Celsius to let that water go. Among common desiccants it has the highest extra binding energy and so the poorest energy efficiency for water harvesting. See heat of adsorption.
Back to top
