Distillation

Distillation is nature’s own way of cleaning water: The solid water evaporates, becomes a gas and reunites into a solid in the form of rain. This life-giving “trick” is that whatever is in the water, besides water, will not evaporate into a gas and will simply be left behind. WaterStillar® produces clean H2O with a natural content of O2 and CO2. There is no difference in water quality whether a small or large amount is produced – there is no correlation between capacity and quality.

Purified or “still” water may also be water that is cleaned through reverse osmosis or deionization. But distilled water should be the process of evaporation and condensation in order not to confuse the terms and technologies.

Designing a distillation apparatus, such as the WaterStillar systems, we have considered and balanced out cost, power consumption, rigidity, migration issues, life span, simplicity, maintenance, and performance. Then, we put it into a Danish design.

Ice cubes from distilled water are crystal clear.
  • Evaporation without boiling gives the cleanest water quality
  • No physical contact between drink water and feedwater
  • High temperatures keep bacteria growth at an absolute minimum
  • WaterStillar® systems are opaque and therefore prevents algae growth
  • Steam is aggressive and will bind unwanted metal ions. Therefore a special glass/ceramic material or food grade stainless steel is used. No plastic. 
  • Taste is neutral, minerals/gas/flavors can be added for desired water taste and health reasons
  • Organic solvents (e.g. petrol, oil, pesticides, chlorine) will evaporate just like water. But these substances are removed by an activated carbon pre- or post-treatment filter.

Distillation vs filters

Filters are designed to filter out substances. That is, filters prevent some substances from passing through. Therefore, they clog. Distillation is different….distillation takes water out of water and leaves everything else behind – besides components that will evaporate along with water and then is removed by a simple carbon filter.

Filters are wonderful and come in many types, sizes and qualities. It is possible to filter to the same quality as distillation – with a lot less energy and a bigger yield than distillation – but there are some drawbacks :

  • Filters hold back the components we want to get out of the water. And then they clog and need cleaning/replacement.
  • Filters, therefore, get more and more ineffective as they get full of components. And then they clog up completely.
  • Filters are a playground for biofouling
  • Designing the right set of filters requires a full understanding of the feed water properties. When the feed water then changes, someone has to monitor this and redesign the filters to keep up.
  • Often there is a rather big ratio of wastewater to produce clean water – RO membranes often need 2-5 times
  • The finer filtering needs to be, the more important prefiltering needs to be. Otherwise, filters can clog in hours.
  • Chemicals for cleaning/backflushing filters create a waste problem
  • High-pressure water treatment brings water off balance and it needs to be stabilised in a post-treatment.
  • The total cost per liter of desalinated water from small RO systems compared to distillation systems are quite close. In large desalination systems with monitoring and trained personnel, it is much cheaper per liter. No contest here.
Micrometers(log-scale) Relative sizeof commoncontaminants Suitablepurificationmethod 0.001 μm 0.01 μm 0.1 μm 1 μm 10 μm 100 μm Aqueus salts Atomicradius Sugar Metal-ion Pesticide Herbicide Virus Gelatin Latex / emulsion Asbestos Paint pigment Bacteria Fine dust / powder Indigo dye Reverse osmosis Nanofiltration Ultrafiltration Microfiltration Particle filtration Distillation

Comparison – bottles, carbon, RO and distillation

The below table is not complete. Please look at the contaminants page to get a better insight.


Bottled Water Carbon filter Reverse Osmosis WaterStillar
Salts
Aluminum
Arsenic
Asbestos
Chloride
Chlorine
Chromium (III)
Chromium(IV)
Copper
Flouride
Lead
Mercury
Nitrate
Phosphate
Sodium
Sulfate
Dissolved solids
Organics
Bromoform
Herbicides
MTBE
Pesticides
THMs
VOCs
Microorganisms
Bacteria
Cysts
Viruses

Applicable with carbon-filter post-treatment

WaterStillar water is distilled water that is produced without tricks. No filters, pressure or other mechanical contraptions that will enhance the yield. WaterStillar water is clean, non-aggressive water and does not contain minerals. If desired, remineralised water is obtained by adding minerals as a post-treatment process along with, ie. aeration. Taste is neutral.

Energy and small volumes

The amount of energy required to vaporize a liquid is called the heat of vaporization. For water, this amounts to 2,256 kilojoules per kilogram at 100°C (970 Btu per pound at 212°F). The same amount of heat must be removed from the vapor to condense it back to liquid at the boiling point.

Distillation is today by far not the most effective way of cleaning water due to the huge energy demand. Therefore some “tricks” are seen to improve the effectiveness.  The heat generated from vapor condensation is transferred to feed water to cause its vaporization and thus improve the thermal efficiency – this is what WaterStillar Works does by reusing this condensation energy in 9 effects. This increases production in a given area and makes it possible to run the system on electrical supplement power during nighttime.

Another “trick” is to lower the pressure and boil water at a lower temperature. In this way, the production rate goes up but introduces other problems with higher complexity and biofouling.

There are a few, new and big solutions (eg. California, Spain) that make cubic meters of purified water through distillation. But most water distillation systems today are making liters for drinking purposes or where extremely clean water is needed (dental, pharma, medic, process water).

Unlimited use

WaterStillar® water may be used for any purpose:

  • Better tasting tea and coffee. Eliminates scale build-up on pots and tea kettles
  • Crystal clear ice cubes
  • Use it for all cooking and baking
  • Excellent for mixing powdered milk, juice mixes and dehydrated soups
  • Use it for all infant care  
  • Excellent for low sodium diets or sensitive stomachs
  • Pure drinking water for your pets
  • Watering your plants – flowers keep fresh for longer time
  • Spraying house plants – no spots on leaves
  • Brushing your teeth
  • Contact lenses
  • Steam irons, humidifiers, vaporizers and car batteries
  • Water for injection (prep with salt/medicine) in remote places
  • Process water in food industry
  • and much more. There are no restrictions.

Keeping water clean and fresh

It is not good enough only to clean water. It is quite as important to keep water clean. Enemies of initially clean water are time, biofouling, migration of chemicals and the right maintenance.

Time

Making clean water is for most water cleaning technologies, not a difficult thing to do. It is possible to discuss the term clean water, but keeping water drinkable over time is another challenge that is often not addressed. All technologies have pros and cons, and therefore the best choice varies from case to case.

Any water test around the world will have a bacteria test for e coli and for slowly growing bacteria. Bacteria grow in numbers when conditions are right and then they just need time. Any open container with water will collect airborne virus and bacteria. Any non-sterile container will grow bacteria when water is added. The “risk” of infected water is similar to any other food that is not kept, handled, stored in a proper way. 

This is why water bottles are relatively safe. They give us a closed environment for safe storage of water. This is why kilometers of pipes with public water supply is a challenge: bacteria grow here and therefore chlorine is used to keep the number of bacteria down. 

Water cleaning technologies in themselves also have a profile, when it comes to initial performance and then over time. Here, distillation at high temperatures outperform any other water cleaning technology. 

Biofouling

Water is our most important food and just like any other food, we need to keep it clean. 

Biofouling is referred to as the unwanted deposition and growth of biofilms and is almost impossible to avoid in moist/wet surroundings. Any water system will have biofouling, including WaterStillar. Biofouling can occur in an extremely wide range of situations, from the colonisation of medical devices to the production of ultra-pure, drinking and process water and the fouling of ship hulls, pipelines and reservoirs. Although biofouling occurs in such different areas, it has a common cause, which is the biofilm. Biofilms are the most successful form of life on Earth and tolerate high amounts of biocides.

There are a number of ways to keep control over biofouling, here are 3 commonly used in the public water supply:

  • Water chlorination is the process of adding chlorine (Cl2) or hypochlorite to water. This method is used to kill certain bacteria and other microbes in tap water as chlorine is highly toxic. In particular, chlorination is used to prevent the spread of waterborne diseases such as cholera, dysentery, and typhoid.
  • Ozonation alternative to chlorination is more cost effective but energy intensive. It involves ozone being bubbled through the water, breaking down all parasites, bacteria, and all other harmful organic substances. However, this method leaves no residual ozone to control contamination of the water after the process has been completed. The advantage of chlorine in comparison to ozone is that the residual persists in the water for an extended period of time. This feature allows the chlorine to travel through the water supply system, effectively controlling pathogenic backflow contamination. In a large system this may not be adequate, and so chlorine levels may be boosted at points in the distribution system, or chloramine may be used, which remains in the water for longer before reacting or dissipating
  • UV treatment leaves minimal residue in the water. In water, UV generates ozone in situ and thus has many of the advantages of ozone disinfection. However, ultraviolet germicidal irradiation alone (as well as chlorination alone) will not remove toxins from bacteria, pesticides, heavy metals, etc. from water.

Biofouling will occur in a matter of hours/days under the right circumstances. So the solution is to have water cleaning device as close to the point of use and then maintaining the device according to instructions and the feed water quality. Filters are a commonly used device and they must be periodically replaced otherwise the bacterial content of the water may actually increase due to the growth of bacteria within the filter unit.

WaterStillar (and other tabletop distillers) including a carbon pre- or post filter can claim to clean water to the highest possible degree. But still, the piping from the system to the tap must be cleaned periodically – and therefore also kept as short as possible.

Migration of chemicals, salts and metals

Water absorbs just about everything. Cuts through mountains and moves otherwise hard substances around in our world.

Whenever food is placed in contact with another substance, there is a risk that chemicals from the contact material may migrate into the water. These chemicals may be harmful if ingested in large quantities or impart a taint or odour to the water, negatively affecting the sensorial quality. The same goes for food. Food packaging is the most obvious example of a food contact material. As the demand for pre-packaged foods/bottled water increases, so might the potential risk to consumers from the release of chemicals into the food and water.

Acceleration of migration is typically pressure, temperature, movement, surface area and time. Elements that any kitchen, barista or laboratory know how to use – whether we need a good fond, a great coffee or an extract for perfumes.

WaterStillar systems are all built with food-safe materials (stainless steel, enamel and glass) and no plastics. For practical reasons a food-grade plastic tube from the system to your kitchen may be used – but we recommend as short a distance as possible. Then the contact time should not cause any problems.

Maintenance – deposits

When water is cleaned, the elements in water are left behind. Hard water is water that has high mineral content. Hard water is typically formed when water percolates through deposits of limestone and chalk which are largely made up of calcium and magnesium carbonates.

Getting rid of these deposits is a matter of manual cleaning, using a locally available de-scaling agent. Typically used for coffee machines. Follow the safety instructions and wear proper protection. The need for cleaning is according to your feed water – a lot of deposits call for cleaning often and make sure the WaterStillar system is performing at its best. The drinking water quality will always be the same, but the daily production will go down if the inside is full of calcium.

So, what is wrong with plastic water bottles ?

To bottle water in order to preserve, make it handy and keep water drinkable is quite smart. Plastic water bottles are here to stay and it is very hard to imagine a world without bottled water. But the problems related to bottled water, in general are many: cost, waste, transportation, chemicals, carbon footprint, space and perhaps more.

In average, every liter of bottled water uses 3 liters of feed water and 1/4 liter of oil (the bottle itself, energy for filtering and transportation). 

Bottled water is in most cases natural water (spring or ground) that is filtered and bottled. The water quality in most cases is very high and monitored under local regulations. Although the general high quality of bottled water, numerous scientific studies show that the quality is questionable in regard of the following:

Chemicals in bottled water come from 3 sources: From the initial water source, the water treatment and chemical migration from plastic bottles into the water. Chemical migration from the plastic bottles is problematic for some plastic types (3, 6 and 7) and less problematic for the most common type (1). The problems with chemical migrations are bigger when the water gets hot, is stored for a long time and if the plastic bottles are reused.

Plastic waste and micro plastic is not only the 1 million bottles sold every minute (2017) but also the micro plastic that is in bottled water (and most other foods/beverages). This means that even if we do not want to, we consume plastic chemicals on a daily basis. There are thousands of different chemicals and the cocktail effects from these are not understood.

Bacteriology measured at standardized tests at 22°C and 37°C show in some studies (too) high values for bacteria count and the water does not meet the limits in EU or WHO directives for water quality. When plastic bottles are reused/recycled the problems are bigger

Taste is individual and humans are able to detect even very small differences. Still, most do not like the taste of warm plastic which is unavoidable in plastic bottled water.

We trust our tap water, right? Well, in many places you can. But there is a clear tendency towards our tap water being problematic for drinking purposes.

This we know, since EWG in the US (a non-profit, non-partisan organisation dedicated to protecting human health and the environment) has looked into this. EWG collected data from state agencies and the EPA for drinking water tests conducted from 2010 to 2015 by 48,712 water utilities in 50 states. All told, the utilities, which had the opportunity to review the data for accuracy, tested for 500 different contaminants and found 267. Contaminants detected included:

  • 93 linked to an increased risk of cancer. More than 40,000 systems had detections of known or likely carcinogens exceeding established federal or state health guidelines – levels that pose only negligible health risks but are not legally enforceable.
  • 78 associated with brain and nervous system damage.
  • 63 connected to developmental harm to children or fetuses.
  • 38 that may cause fertility problems.
  • 45 linked to hormonal disruption.

EWG has concluded that there are 11 common pollutants found in tap water across the US:

  1. Chlorine is used to sanitize water, but is highly toxic
  2. Fluoride is often added to water to reduce tooth decay but is related to a number of illnesses
  3. Bacteria and vira. Despite chlorination, not all (harmful) bacteria and vira can be killed/eliminated. 
  4. PCB’s are polychlorinated biphenyls, an industrial chemical that was banned in 1979 and still here
  5. Lead is highly toxic to humans and migrates typically from pipes, water taps and landfills
  6. Pesticides and herbicides are agricultural chemicals that slowly but surely turns up in our groundwater
  7. Nitrate is used to provide nitrogen to plants and ends up in our water ways
  8. Mercury is highly toxic to humans
  9. Drugs and hormones are found since they are difficult to eliminate in sewage plants
  10. Heavy metals – such as chromium, cadmium, barium and arsenic
  11. Radioactive tap water. Radium. 

Is distilled water aggressive ?

Again, there is no simple answer. Aggressiveness or corrosivity in water is, in general, a complex interaction between water and metal surfaces and materials in which the water is stored or transported.  The corrosion process is an oxidation / reduction reaction that returns refined or processed metals to their more stable and natural ore state. Any hotel using espresso machines on RO-water that has not been post treated sufficiently will tell that the machines needs replacement very often.

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