Drinking distilled water

Introduction

I make distilled water at home and drink it as my primary form of hydration since the year 2020. I choose to do it partly for the taste – I mildly dislike the moderate amount of minerals in Toronto tap water. And partly for safety – the distilled water is guaranteed to be free of pathogens, heavy metals, microplastics, pharmaceuticals, etc.

Contrary to popular belief, distilled water does not “strip minerals from your body”, and drinking it has no long-term harm. At the same time, I reject any claims about special healing properties of distilled water. Rather, I consider it as a neutral reference baseline that all other forms of water must be benchmarked against.

Having evaluated many different options for obtaining and/or filtering water, I settled on distillation because it is simple, reliable, and cost-effective. Other alternatives like reverse osmosis (my second choice), filters, and bottled water (filtered commercially) have characteristics that are less desirable to me.

Here I will discuss a multitude of considerations related to distillation as well as purifying water in general.

Distillation process

Distillation is a physical (not chemical) process that involves heating the water to a boil, extracting the steam from above, leaving behind all other dissolved chemicals and impurities, and cooling the steam to condense it back into pure water.

This is an easy process to understand and hard to hide anything nefarious. It is also completely natural, as rain is a form of distilled water (with minute amounts of air pollution). There are no complicated chemicals or chemistry involved, unlike other water treatment options that involve semi-permeable membranes, ion-exchange resins, activated carbon, activated alumina, proprietary materials, and so on.

The main consumable of distillation is heat energy, which is most conveniently delivered as electricity. A minor consumable is acid (usually citric acid) for removing mineral build-up in the boiler. An optional minor consumable is activated carbon/charcoal for removing potential VOCs in the distilled output.

The machine that I use is made by Megahome, a Taiwanese company with decades of history since 1993. The appliance is UL-certified and comes with a glass carafe. Other brands with comparable products exist, but they seem to have less history and reputation.

More info: CenturyLife.Org: In-Depth Product Review: Megahome Countertop Water Distiller, Glass Collection (White Enamel or Stainless Steel Finish)

Other water options

These are listed from easiest to most difficult.

Tap water

In developed countries such as Canada, every city has a public water system that is safe to drink from and is continuously monitored by professionals. I have drunk straight from the tap for much of my life, with no known negative effects. This is by far the cheapest and easiest option, to rely solely on the municipal water supply, involving no extra effort.

The City of Toronto even boasts its clean water by making it freely available at popular street events – they roll a cart that has a number of taps and fountains for people to use, and connect it to a fire hydrant. Other than that, the city publishes reports about the hundreds of chemicals that they test for in tap water.

Boiling

Heating up water in a kettle is a common and easy way to make water safer, destroying pathogens such as bacteria and viruses. It does not remove minerals or simple organic compounds (PFAS, etc.). When a public water source experiences potential contamination or a loss of pressurization, government officials tell residents to boil the water before drinking it. Drinking hot water is popular in Chinese culture as they believe that it is good for the body and cold water is bad (I reject this superstitious belief).

Bottled water

Some people don’t trust their city’s water supply and instead buy water from grocery stores, convenience stores, or dedicated water stores, and then manually transport it home. The vast majority of such people buy single-use plastic bottles, which are not only unnecessarily expensive, but whose manufacture and disposal are environmentally damaging. Some people bring their own bottles to fill at the store, often in sensibly big sizes like ~20 litres.

The water ultimately comes from somewhere. Some bottled water comes from natural springs, while others are derived from municipal tap water – either used straight, or further processed with reverse osmosis, filtering, and/or remineralization. So, bottled water isn’t some magical golden source of water, but it gives you access to sources that are outside of your immediate city, and it also bypasses any potential issues with contamination introduced in the kilometres of pipes from the water treatment facility to your home. However, news reports indicate that in many jurisdictions, tap water is regulated and monitored to a higher standard than bottled water.

More info: YouTube: Future Proof - Bottled Water is Literally a SCAM

Filtering

I used Brita filters for some years of my life and do not look fondly on that experience. To start, I have to soak a filter before using it. For the first few runs, I get fine black particles in the filtered output, which look dubious but are harmless (probably the activated carbon). The taste of the output is quite variable – I might be able to taste the carbon, and the ion-exchange beads quickly lose their effectiveness in removing calcium and magnesium from Toronto tap water. I have to wash the water pitcher every few weeks, which requires manual dexterity. Worse, I sometimes find green stuff (algae?) growing in the water pitcher, and I’m not sure if that’s harmful to drink. Finally, the filter has to be changed every month or two as it loses effectiveness. Apparently, a standard Brita filter is rated for 150 L of water, and in the year 2023 it costs around 7 CAD each.

Brita is by far the most popular brand of water filter and their products are sold around the world. But in my opinion, they are the least sophisticated, least effective filters. Other brands exist and have their own unique selling points, but the companies are newer, the products are more expensive, and the longevity of these companies is dubious. I have not tried other filter systems and cannot comment on much, other than the fact that they don’t appeal to me on features or price.

More info: YouTube: Future Proof - Why are Brita Filters SO Popular?

Reverse osmosis

RO involves pushing water through a semi-permeable membrane such that minerals and other dissolved solids are left behind. It’s an incredible technology that is competitive with distillation, where each one has a set of applications where it is the best solution. For example, RO is used in many city-level desalination systems, RO is common in homes if the household chooses to have any water treatment system at all, and some bottled water brands are just municipal tap water with an additional RO step. Treating a given volume of water with RO takes several times less energy than distillation, which matters significantly at industrial scales like serving a city.

RO also has a number of downsides, as with any technology. It requires high-grade mechanical energy for pumping, whereas distillation can take waste heat from engines and power plants. RO rejects more wastewater than distillation – it needs to flush the membrane, and sometimes needs to boost the incoming water pressure via hydraulic ramming. RO membranes can be damaged by very hot water. RO requires non-trivial engineering, maintenance, and replacement for the membrane, pre-filters, and post-filters.

More info: YouTube: Water Nerd TV - 5 Problems With Reverse Osmosis Water Filters

General considerations

Consumables and cost

Distillation: The machine costs anywhere from 100 to 300 USD. Energy use is around 0.7 kW⋅h/L (or 2.5 MJ/L). If we assume the cost of electricity to be 0.20 USD/(kW⋅h), then that translates to around $0.14/L. This is roughly 1/3× to 1/10× the cost of bottled water and avoids producing plastic waste.
Bottled water: As one data point, 4 L of distilled water can be purchased at most grocery stores for 1 to 2 USD. This translates to a cost of about $0.25 to $0.50 per litre. Other data points exist, but the cost is unlikely to differ by more than 1/3× to 3×. Overall, this is in the same price range as distillation.
Brita filter system: A pitcher is around 20 USD (a fixed cost). A filter is around 5 USD and is rated for 150 L of water (though in actuality it depends on the initial purity of your water). This translates to a cost of about $0.03/L, but the quality of the output is nowhere as good as distillation.
ZeroWater filter system: A pitcher is around 30 USD. A filter is around 12 USD and is rated for 57 L of water. This translates to a cost of about $0.21/L. The official recommendation is to replace the filter when the TDS reading reaches 6 ppm. Meanwhile, distillation consistently produces water at 3 ppm, requires no filter changes, and costs about the same per litre.
Waterdrop reverse-osmosis system: The equipment costs 400 USD. The reverse osmosis filter costs 110 USD and is rated for 8300 L of water. The sediment and activated carbon pre-filter is 30 USD for 2100 L. The activated carbon post-filter is 30 USD for 4200 L. All in all, this translates to a cost of about $0.03/L, the same as Brita but producing much higher quality water.

Distillation involves buying a machine once and then only paying for electricity thereafter. Reverse osmosis and filtering involve plastic cartridges that contain membranes, ion beads, activated carbon, etc. that eventually wear out. These cartridges need to be replaced periodically, anywhere from once a month to once a year. The products are often proprietary, making you dependent on a single company for replacement parts and pricing. To make matters worse, the companies that make these water purification systems and consumable filters sometimes go out of business in years or decades, forcing you to eventually buy a new system.

More info: YouTube: Practical Engineering - Why Is Desalination So Difficult?

Applications

I use distilled water for drinking because I prefer the sweet taste of pure water. I use ordinary Toronto tap water for cooking (e.g. rice and noodles), rinsing fruits and vegetables, brushing teeth, showering, laundry, etc. because it is safe and cheap, and the mineral content is not unreasonably high. I sporadically use distilled water for cleaning, such as wiping windows and mirrors, because the lack of calcium and minerals guarantees no streaks and residues after evaporation. If I used devices such as irons, ultrasonic humidifiers, CPAP machines, and car batteries, I would definitely supply them with my homemade distilled water.

If I lived in a place with harder water, I might shift more of my domestic water applications to treated water. For example, I might cook with treated water, I might find that soaps in the shower and laundry work poorly in hard water, etc. Because distillation is only good for low-volume applications, I would instead add a water softener and/or whole-home reverse-osmosis system for the other uses.

Minerals

There is a widespread myth that drinking distilled water is harmful because it contains no minerals, therefore it depletes your body’s store of minerals. This belief is wrong on many levels.

First, there are places in the world where the water is naturally soft and contains little mineral content. I drank tap water in Ottawa (Canada) and various cities in Japan, and it was softer than Toronto water. Yet, there is no public health crisis or outcry about the water in these places. The people there are healthy and the water doesn’t need to be modified.

Second, all drinkable water has less mineral content than the cells in our bodies. The overall salt content of humans is around 0.4% by weight. In blood, it is around 0.9%, or 9000 ppm – this is why saline solutions for intravenous injections are prepared at this concentration. The water we drink is all hypotonic, yet our cells don’t explode every time we drink water.

If minerals from drinking water are largely ignorable, where do we get them from? From food, of course. Plants and animals incorporate minerals into their tissues, and we get our necessary minerals from the food we eat.

Fluoride

Fluoride is a negatively charged ion that has benefits and drawbacks. In the right amounts, it creates stronger teeth in the form of fluorapatite. In excessive amounts, fluorosis damages bones and joints. Fluoride can be found in many natural water sources, and municipalities add or remove fluoride in order to target the optimal safe amount.

I do not consider fluoride a poison, unlike many people who seek treated water. But because distilled water inherently has no fluoride ions, I partly rely on toothpaste to spread fluoride on my teeth.

More info: YouTube: Professor Dave Explains - Lies People Tell About Water – Part 1: Water Fluoridation

Total dissolved solids measurements

A quick and cheap way to check the purity of water is to use a TDS meter, which measures electrical conductivity. It requires no chemicals, processing time, or expensive materials/machines. While it doesn’t measure everything in the water, it is a good enough approximation for most purposes. In particular, a high reading guarantees that there is significant mineral content in the water, whereas a low reading could mean the water is pure or there are still other unmeasured chemicals present.

TDS values are conventionally quoted in parts per million (ppm) by mass. 1 ppm equals 1 mg of dissolved solids per 1 L (or 1 kg) of water. Some values of personal significance (ppm):

400: Some brands of bottled spring water, and some cities I visited with very hard water. I really dislike the taste.
130: City of Toronto tap water. Having lived almost my entire life with this, I consider the hardness to be middle or average.
3: The output of my water distiller. I believe the non-zero reading is explained by the water capturing minute amounts of carbon dioxide (CO₂) from the air and producing a tiny bit of carbonic acid, which is conductive.
0: Melted ice from some hotel ice maker machine in Montréal. The local tap water was 130, so the machine was definitely fed with extra-treated water. But after leaving the melted ice water exposed to the air for a day, the reading was 3.

Consistency

Distillation is remarkable for producing consistently high-quality water every time. This is true even if the boiler gets coated with minerals from previous runs. Other water purification methods inherently cannot attain the same level of consistency. Filters get clogged with impurities and lose effectiveness at capturing impurities. Reverse osmosis membranes can be damaged by chlorine and can also get clogged with use. Activated carbon gets saturated with impurities and loses effectiveness. Ion exchange resins are inherently consumable as they absorb calcium and other ions while releasing protons and hydroxides. Distillation suffers from none of these drawbacks, and its main consumable is electricity. It is a nearly unfuckupable way to purify water.

Material contamination

Distillers are very good in this department. The boiler is stainless steel, the condenser tube is stainless, and the collection jar is glass (or plastic if you choose). You have the option to add an activated carbon filter to reduce VOCs, and activated carbon is a well-known food-safe ingredient. This absolutely minimizes any harmful substances being leached into the distilled water. Distillation is very transparent about its process and materials, and it is hard to hide problems in such a simple system.

By contrast, RO and filter systems have many plastic parts, which come with all the usual health concerns about BPA, Tritan, microplastics, etc. Moreover, the membranes and filters contain various chemicals that could have their own known and unknown risks, and sometimes the composition of these parts is proprietary and not openly documented.

Questionable water sources

Suppose you take water from a random pond or river. Would you drink it? Maybe it contains bacteria, animal manure, heavy metals, and organic chemicals.

Boiling the water kills pathogens but doesn’t remove chemicals. Filtering and RO are not 100% effective, and impurities can still slip through. Filters also get less effective over time as they get clogged with impurities from previous runs.

Distillation is the only method that produces safe treated water with a high degree of confidence. To be extra safe, you can discard the first part of the distilled output in case there are chemicals with a lower boiling point with water, and you can pass the wanted distilled water through an activated carbon filter to grab any VOCs that might slip through.

Note that I would not recommend taking water from a road puddle, even for distillation, because there could be a substantial amount of contamination from petroleum products.

Off-grid living

Distillation is a great method of water treatment for off-grid living with few dependencies. It can make questionable water sources safe in a way that filtering and other methods can’t. It consumes electrical energy, which can be obtained from on-site solar and wind generators. It doesn’t consume filters and RO membranes, which require nontrivial technology to manufacture.

Marketing

Various brands of bottled water can be found at almost every food store. Some brands boast qualities such as vitamins, minerals, alkalinity, etc. Some can be found on billboards and TV commercials. Clearly a lot of effort has gone into marketing these products.
There are so many water filtration systems that it’s impossible to count them all. Some can be found in physical stores, ready to be plucked off the shelf by an unsophisticated consumer. Some have flashy websites and ad campaigns to boast their merits.
Reverse-osmosis systems are easy to find once you go to specialty water shops. They show up readily in online search results for “water purifier”, whether on Google or Amazon, though they are less popular than filter-only systems (note that RO systems have some filtration steps as well).
Distillers are hard to find by accident, and I feel like you have to ask for such products specifically by name in order to get any search results. They tend not to show up when searching for “water purifier” or synonyms thereof, and they don’t seem to have any ad campaigns or slick websites.

Overall, I find it strange that water distillers are so poorly marketed compared to all the other alternatives. Maybe it’s because distillers are simple machines and don’t require purchasing a perpetual supply of proprietary replacement filters, so they’re not as profitable as other products. Or maybe it’s because people have a preconceived notion that water treatment equals filtering, completely forgetting that boiling is a form of treatment too.

Health claims

I drink distilled water because it tastes good and is safe. However, many businesses try to market distilled or other types of water as having unique health benefits. I categorically reject any claims related to:

Alkaline water
Raw water
Structured water
Detoxification
Curing cancer

More info:

Distillation considerations

Descaling with acid

As the water boils off, the concentration of minerals and solutes in the boiler chamber increases until they can no longer stay in solution and they precipitate out as solids. Essentially, white rock and powder such as calcium form on the walls of the boiler. The standard way to deal with this is to fill the boiler with an acidic solution – usually citric acid or acetic acid (vinegar) – have it dissolve the minerals back into solution, and flush the solution.

To reduce the descaling burden and eliminate foul burnt odors, I find it helpful to stop the distillation process before the boiler runs dry, at roughly the 5% water mark. This is best done with a shut-off timer, with the running time derived from manual observation.

Removing limescale from the boiler walls is not time-sensitive at all. Most importantly, it does not affect the quality of the distilled water output. It can take many millimetres of limescale before issues like reduced heat conductance and reduced tank volume have any practical impact. However, aesthetics can be a reason to descale regularly, as clean stainless steel looks better than a mess of powdery mineral build-up. Moreover, descaling does need to be performed eventually because a high amount of deposited minerals physically clogs up the boiler.

The need to descale is not unique to distillation; any process that removes minerals from water is liable to have minerals deposited somewhere else. For reverse osmosis, there is a dedicated wastewater path, and flushing out solutes is designed into the process. For filtration, minerals adhere to the filters and the filters need to be changed periodically. Even kettles need to be descaled because the high temperature causes calcium carbonate (CaCO₃) to precipitate out of solution, though the amount of descaling needed is far less than that of distillation.

Volatile organic compounds

Some chemicals are not easily removed by distillation. If the source water contains chemicals with a lower boiling point than water – like ethanol – then it is prudent to discard some initial amount of the output distillate until you are reasonably confident that the current output is pure water. Another weakness is that distillation cannot disturb azeotropes like water and toluene. But if you have to worry about azeotropes, your source water is very sketchy, and you should consider getting a better water source and possibly a degree in chemistry to understand all the nuances of distillation.

For the distillation of sane water supplies, VOCs are generally handled by placing an activated carbon filter at the output. While this approach is imperfect, it is more than good enough for the real world.

Stocking up

I put aside several litres of homemade distilled water in glass jars as an emergency preparedness measure. This helps me survive the loss of tap water and electricity for a few days. Distillation is important because it is absolutely guaranteed to destroy and remove all microorganisms while other filtration methods do not. Glass is important because unlike plastic and steel, it is very inert and doesn’t leach any chemicals into the water. Both factors contribute to the safe long-term storage of water for contingency use.

Future improvements

The currently available home countertop water distillers are not the pinnacle of technology. Far from it, they represent the most basic working design that leaves many things to be desired.

For starters, they are horrendously energy-inefficient. For every drop of water that is processed, heat is added until it boils, then all that heat is dumped into the air when the water condenses. A far more sensible approach is to capture and reuse that heat to boil more water, instead of adding new heat. Indeed, industrial-scale water distillation achieves this heat reuse through multiple-effect distillation and multi-stage flash distillation. I wish some of these designs would trickle down into the home market, as energy is by far the main cost of distillation. From some back-of-the-envelope calculations, I noticed that industrial distillers are an order of magnitude more efficient – they produce 10× the volume of water for the same amount of input energy. This could make distillation cost-competitive with other methods of water treatment.

Home distiller machines all seem to have the same appliance shape and same liquid capacity of ~4 L (or 1 gallon). There is no attempt to serve different needs such as larger families or portable travel versions. There are also no tankless systems where the distiller machine only performs the boiling, condensation, and waste rejection, but isn’t responsible for storing water. In such a setup, you would supply your own hoses and containers, you can size the reservoirs however you like, and you could even use the tap as a continuous source.