After several months of increasing my water intake, I wanted to see if a home water purification system would be more efficient than buying bottled water all the time. I reviewed the different systems out there and decided to install a water distillation unit in my home. Now I enjoy pure water and crystal clear ice cubes any time I want them.
What Is Distillation?
This type of water purification is one of the oldest and most reliable purification processes.
The US Environmental Protection Agency (EPA) states that distilled water can be classified as purified water because it “…[does] not contain more than 10 parts per million of total dissolved solids [TDS].”
Why Do Total Dissolved Solids Matter?
TDS most often refers to:
- any substances in the water that are not water molecules themselves. According to the University of Wyoming Extension, TDS is “… all inorganic and organic substances contained in water that can pass through a 2 micron filter.”
So 2 microns is pretty tiny!
Suspended solids found in raw water are not as big a concern because they are almost always larger than 2 microns in diameter. They are left behind during the distillation process. These solids include:
- algae and plankton
- clay and silt
- other organic debris
They also state that distillation is one of the few ways to protect yourself from contracting the parasite Cryptosporidium (Crypto) from your drinking water.
It remains the “leading cause of waterborne disease outbreaks.” Believe it or not, Crypto still infects about 750,000 people in the United States each year, resulting in debilitating diarrhea that sometimes continues for weeks!
According to the CDC (Centers for Disease Control and Prevention), this germ can’t be killed by chlorine because of its hard outer shell. So drinking water treated with chlorine can still carry this germ from your tap to your glass.
How distillation works
It mimics the natural hydrologic cycle, which is just a fancy way of saying how water naturally moves through the environment in a continual motion.
Remember that water cycle illustration you learned from in grade school? It showed a bit of land at the edge, the sun and some clouds in the sky and ocean water across the bottom.
The sun heats up the water and creates vapor that moves up into the sky, forming clouds. After enough vapor gathers, water leaves the clouds as precipitation (rain or snow), falling back down to the land and sea. Then the cycle repeats and continues forever (or so we hope).
Distillation of water follows that model.
- Water from your home’s cold water line enters the distillation system. For counter-top models, you pour cold tap water into the unit.
- Water is heated to its boiling point in order to make a vapor. This stage of the process separates the water from any minerals, chemicals, microorganisms and other sediment it may contain.
- The vapor passes through coils that are cooled by either air or cold water.
- As the vapor temperature drops, it condenses back into liquid water.
- The purified water is collected in a tank.
- You control a spout at the bottom of the tank to pour out clean water.
While chemicals can be removed from the water, it is important to remember that the process is not a chemical one but a physical one. No chemicals are added to purify your drinking water.
As the educational website Byju’s puts it, “[t]he process of distillation exploits the difference in the boiling points of the components in the liquid mixture by forcing one of them into a gaseous state.”
What Are the Pros and Cons of Distillation?
As with any water purification system, there are advantages and disadvantages. Research your options to make sure you choose the right type of unit for your home.
- Distillation is very efficient at removing contaminants such as bacteria, viruses, parasites, heavy metals and other sediment. This quality makes it an attractive option for homes that rely on well water and for people with compromised immune systems.
- The availability of counter-top/freestanding models make it a good option for renters or others who don’t want to make permanent changes to their home.
- It reduces hard water problems because it removes the soluble minerals that can cause damage to fixtures and appliances.
- Distillation systems are low-maintenance, only requiring occasional replacement of the carbon filter, in models that include one.
- Different unit sizes are available so you can choose the capacity that suits your needs.
- It is easy to tailor mineral content by adding your preferred mix of mineral drops to the purified water. This allows you to make your own purified alkaline water that tastes good and has increased hydrating qualities.
- One major argument of opponents of distillation is that it removes all of the minerals. This results in an acidic pH, zero nutritional value and a flat taste.
- The heat required will add to your energy costs. For larger units, the heat generated can also contribute to the temperature of your home.
- Some harmful elements are not removed because they have a boiling point that is lower than or equal to water (pesticides, chlorine and herbicides, for example). The EPA warns that “[c]ontaminants that easily turn into gases,such as gasoline components or radon, may remain in the water unless the system is specifically designed to remove them.”
- Volatile petroleum chemicals and volatile organic compounds can be evaporated with the water and end up in your drinking glass. Activated carbon added to the system can filter these elements out.
- When used to make seawater potable, some of the solids in the water become thick and sticky when boiled, and “[t]he congealed solids are deposited on the surface of the heat exchanger causing further reduction in efficiency.”
- It is a slow process that can require a few hours to produce one gallon of purified water.
What Are Some Other Uses for Distillation?
Aside from purifying drinking water, distillation is used in several industries to make a wide range of products.
- Healthcare applications include using distilled water to adjust the concentrate of medications and vaccines.
- Batteries and humidifiers require distilled water to function properly.
- Alcoholic beverages are purified using distillation.
- Essential oils, food flavorings and perfumes use distillation to purify and concentrate the desired products.
- The petroleum industry distills crude oil prior to storing and transporting it.
What About Membrane Distillation?
You may have read of a process called Membrane distillation. This is not the same thing as water distillation. It is a process used in industrial and remote settings. In remote settings it is used for desalination (making drinking water from seawater).
Research published in the January 2013 issue of Water describes membrane distillation as a process that uses differences in vapor pressures to remove several contaminants.
- Microorganisms (bacteria, viruses and parasites)
- Radionuclides (radioactive elements that most often enter the water supply from nuclear power plant runoff)
- Heavy metals
This technology is more expensive than some other purification systems, but it is more efficient than other means when treating very salty water.
The food industry uses membrane distillation to make concentrates of milk, sugars and juices.
What Options Are Available?
There is a variety of residential distillation systems to choose from.
- Counter-top/manual distillers have to be refilled, usually one gallon at a time. The advantage of these is the small amount of space required and the attractive pitcher design. Some counter-top designs come with two carafes so you can have one in the fridge while the other is being filled.
- Freestanding carts can be filled manually, but are too big to fit on the counter-top. These units are tall enough to stand on the floor and still offer easy access to the spout.
- Plumbed/automatic distillers connect directly to a water line inside your home. The advantage of this version is that it produces a continual supply of purified water.
- A range of sizes are available, from units that distill 3 gallons daily to systems that can produce up to 22 gallons a day.
What Are the Installation and Maintenance Requirements?
Countertop and freestanding models don’t require drilling for installation, and in-line designs only require tapping into your kitchen’s cold water line. Some assembly may be required, depending on the model.
You will need to follow the manufacturer’s care instructions for the unit you buy to get the best use out of your distiller. Whichever type you get, the following tips can help.
- When you first start using the distiller, check for buildup once a week. This will give you an idea of how often you will need to clean it. If you have hard water, cleaning will need to be done more frequently to prevent damaging and costly buildup.
- Keep a record of repairs and maintenance performed.
- If applicable, replace the activated carbon filter per manufacturer recommendation.
- Drain some of the water from the boiling reservoir once in a while to minimize the accumulation of sediment.
In general, heating elements can last about 3 years before needing to be replaced.
How Much Does It Cost?
The amount of money you spend on a distillation unit depends on the size you buy. Smaller counter-top units can cost less than $200 while larger, in-line models can cost over $1200.
You will also need to take into consideration the ongoing cost of operation to get an idea of what you are really spending per gallon of purified water.
This cost will vary depending on the type of unit you choose and how cold the feed water is. On average, energy cost ranges from 25 cents to 33 cents per gallon.
What Should You Know Before You Buy?
- Make sure the distiller you want has a sensor to turn off the heat when the boiling chamber runs out of water.
- Confirm that the system is certified by NSF International (formerly the National Sanitation Foundation) and that the installer is certified by the Water Quality Association. The NSF International website has a searchable database of water treatments and filters that they certify.
- Look for a drain opening that lets you easily remove the leftover contaminated water.
- Find out how much water your desired model requires in order to produce pure water. Extension.org, a resource for cooperative extension programs nationwide, states “Air-cooled devices typically produce 1 gallon of untreated water for each gallon of treated water. Water-cooled units may require 5 to 15 gallons of untreated water for each gallon of treated water.”
- Ask about auto-shutoff features that minimize energy cost.
- Ask how long the unit should last, and only purchase a system that comes with a warranty.
How Will You Know if It Really Works?
Because the harmful elements in water cannot always be seen, tasted or smelled, it is important to periodically test your treated water.
- Right after installation, have your water tested by a state-certified lab. The EPA maintains a database of labs by state. Make sure you take samples of both the feed water and the distilled product.
- Have these same samples tested each year to determine repair/replacement needs. Test more frequently if you know your untreated water has a high level of contaminants.
Home water distillation comes with advantages and disadvantages just like any other treatment system. But the variety of design options and the unsurpassed purification achieved with distillation are what won me over.