Distillation is one of the oldest methods of water treatment and is still in use today, though not commonly as a home treatment method. It can effectively remove many contaminants from drinking water, including bacteria, inorganic and many organic compounds.
Your first step toward solving a suspected water quality problem is having your water analyzed by the local health department or a reputable laboratory. A water analysis not only verifies if a water quality problem exists, but is essential to determine the most appropriate solution to the problem. State or local health officials can interpret water analysis results. Some labora- tories may also provide this service.
Home water treatment should be considered only a temporary solution. The best solutions to a contaminated drinking water problem are to stop the practices causing the contamination or change water sources.
Distillation relies on evaporation to purify water. Contaminated water is heated to form steam. Inorganic compounds and large non-volatile organic molecules do not evaporate with the water and are left behind. The steam then cools and condenses to form purified water.
Distillation effectively removes inorganic compounds such as metals (lead), nitrate, and other nuisance particles such as iron and hardness from a con- taminated water supply. The boiling process also kills microorganisms such as bacteria and some viruses. Distillation removes oxygen and some trace metals from water. For this reason some people claim distilled water tastes flat.
Distillation's effectiveness in removing organic compounds varies, depending on such chemical characteristics of the organic compound as solubility and boiling point. Organic compounds with boiling points lower than the boiling point of water (ex. benzene and toluene) vaporize along with the water. These harmful compounds will recontaminate the purified product if not removed prior to condensation.
Distillation units, or stills, generally consist of a boiling chamber, where the water enters, is heated and vaporized; condensing coils or chamber, where the water is cooled and converted back to liquid water; and a storage tank for purified water. Figure 1 shows the parts and process of a distiller.
Distillation units are usually installed as point-of-use (POU) systems. They are generally placed at the kitchen faucet and used to purify water for drinking and cooking only. Size varies, depending on the amount of purified water they produce. Production rates range from 3 to 11 gallons per day. Home stills can be located on the counter or floor, or attached to the wall. Models can be fully or partially automated, or manual.
Some units have columns or volatile gas vents to eliminate organic chemicals with boiling points lower than water, thus ensuring uncontaminated water.
As with all home water treatment systems, distillation units require some level of regular maintenance to keep the unit operating properly. Uneva- porated pollutants left in the boiling chamber need to be regularly flushed to the septic or sewer system. Even with regular removal of the residual water containing unevaporated pollutants, a calcium and magnesium scale will collect at the bottom of the boiling chamber. The scale eventually needs to be removed, usually by hand scrubbing or by using acid.
Heating water to form steam requires energy. Which means the operating costs for distillation units are generally higher than those for other home water treatments. The production of heat from home distillation units can be an advantage in winter, but a disadvantage in summer.
Distillation units are generally expensive, ranging from $300 to $. Port- able units can be purchased for less than $200. (NOTE: Dollar values are provided as a rough guide to compare costs of different systems. Current prices are likely to be higher than those quoted.)
Certification of treatment products is available from independent testing laboratories, such as the National Sanitation Foundation (NSF). Results from NSF tests provide good measures of the effectiveness of devices designed to treat water for both esthetic and health reasons. The Water Quality Associa- tion (WQA) is a self-governing body of manufacturers and distributors. WQA offers voluntary validation programs to its members. Validation is less stringent than certification. Certification or validation does not ensure effective treatment; all systems must be designed for each particular situa- tion and maintained properly.
Treating drinking water by using home distillation units is one option avail- able if you have a water quality problem. Distillation effectively removes inorganic compounds, bacteria, particles and some organic contaminants. How- ever, other treatment methods may be better for these contaminants and more cost-effective as well. Distillation is not a very common method for home water treatment.
For further information on water quality contact your county Cooperative Extension office or local health department. The following bulletins in the WQ series may also be helpful:
- WQ 1 "Water Testing Laboratories"
- WQ 2 "What Is Ground Water?"
- WQ 3 "How to Take a Water Sample"
- WQ 4 "Why Test Your Water?"
- WQ 5 "Interpreting Water Test Results Part One: Inorganic Materials"
- WQ 6 "Buying Home Water Equipment"
- WQ 9 "Water Quality for Animals"
- WQ 10 "Wetlands and Water Quality"
- WQ 11 "Sulphur Water Control"
- WQ 13 "Home Water Treatment Using Activated Carbon"
- WQ 14 "Reverse Osmosis for Home Treatment of Drinking Water"
- WQ 16 "Bacterial Contamination of Household Water"
Kamrin, Michael, Nancy Hayden, Barry Christian, Dan Bennack and Frank D'Itri, WQ 22 "Distillation For Home Water Treatment," Cooperative Extension Service, Michigan State University, .
*Reviewed and revised by Adel Pfeil, Extension Specialist, Department of Con- sumer Sciences and Retailing.
Editor: Cheri L. Janssen, Department of Agronomy
More and more people are starting to realize the benefits of purified, clean, and safe water. Water distillers have gained popularity as one of the most effective methods to purify water for several uses. Water distillers mimic nature's hydrological cycle, where evaporation and condensation constantly strive to maintain a delicate balance in environmental water quality.
Today, water distillers have become more accessible and affordable to the average person. This gives you the option to own a water distillation machine with quality and consistency you can bank on.
In this article, we'll explore water distillers in detail, from how they function to their benefits and flaws. We'll discuss scenarios where water distillers shine and guide you through selecting the perfect one for your needs.
A water distiller is a specialized device designed to purify water by transforming it to vapor and then condensing it back to liquid form.
Water distillers operate on the principles of evaporation and condensation. Evaporation occurs when water is heated to high temperatures. The buildup of thermal energy excites the water molecules, prompting them to break free into a vapor state. During this process, impurities in the water are left behind because they don't have the same boiling point as water.
The water vapor produced by evaporation is directed into a cooling system suitable for condensation. Condensation is the process in which water vapor is converted back to liquid water. Condensation occurs when water vapor is cooled, effectively changing it back to purified water.
The end product, which is pure distilled water, is free from the contaminants left behind during evaporation.
Water distillers are highly effective in eliminating a range of impurities, including heavy metals, unwanted minerals, and other contaminants.
Some contaminants removed by water distillers include:
Apart from these contaminants, water distillers also get rid of disease-causing microorganisms such as bacteria, viruses, and parasites. These microorganisms are unable to withstand high temperatures when water is boiled.
Despite their success with several common water contaminants, water distillers are not fully effective in removing volatile organic compounds (VOCs). VOCs are a group of contaminants with high vapor pressure and low water solubility at room temperature. Popular sources of VOCs include paints, cleaning products, pesticides, petroleum products, and chemicals from manufacturing processes.
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VOCs have a boiling point lower than or close to that of water. Therefore, they evaporate earlier in the distillation process and are present in the steam produced. The best way to remove VOCs is through activated carbon filters.
Luckily, some water distillers in the market are fitted with carbon filters to remove VOCs. If possible, choose a water distiller with a carbon filter to further enhance the quality of your water.
Water distillers excel in many ways, positioning them as a suitable choice for water purification. There are four main advantages of using pure water distillers.
Effective and Consistent Purification
Water distillers produce high-quality purified water by eliminating 99.9% of contaminants. Apart from that, they are also lauded for their consistency. While several factors affect the output quality of other water purification methods, water distillers deliver contaminant-free water throughout their lifespan.
Chemical-Free Purified Water
Water distillers purify water without the need for chemicals like chlorine. Chlorine is usually added to water to get rid of pathogens. However, chlorine imparts an unpleasant taste and odor in drinking water. Water distillers eliminate the need for disinfectants like chlorine. In fact, water distillers help remove residual chlorine from tap water.
Long-Term Cost Efficiency
Many water distillers contain few moving parts and as a result, have few maintenance requirements. Water distillers will also relieve you from the costs of having to purchase bottled water.
Simplicity in Operation
The operation of standard water distillers is straightforward. They also don't require complex installation procedures. This makes them suitable for home use since little or no technical knowledge is required.
Just like any other water filtration method, the use of water distillers comes with some disadvantages. Here are a few drawbacks of using water distillers.
High Energy Consumption
Compared to other water purification methods, water distillers are less energy efficient. The distillation process uses heat to convert water to steam. This requires a high energy input and may increase your electricity bill. However, in the long run, you may be able to offset this extra cost since you won't need to purchase expensive bottled water.
Slow Production Rate
Water distillers have a slower rate of production. The distillation process usually takes a long time, depending on the specific water distiller machine. Water distillers may not be suitable for scenarios where rapid production of pure water is required.
To bypass this setback, investing in an automatic water distiller will ensure that you always have purified water in your reservoir. You can also extract and store distilled water in glass containers and keep them in a refrigerator.
Flat-Tasting Drinking Water
Purified water from distillers lacks the alluring natural taste of water. Distilled water tastes flat because it's low on oxygen. Water distillation also removes minerals from the water. While excessive mineral concentration causes an unpleasant taste, a total lack of minerals results in a flat taste.
High Initial Costs
Water distillers are a bit more costly compared to other water purifiers. The high initial investment is a setback to people on a tight budget. However, the initial investment may be offset in the long run due to lower maintenance costs.
Water distillers need regular maintenance to keep their performance at optimum levels. It's vital to clean the boiling chamber regularly.
During distillation, impurities usually remain in the boiling chamber as water evaporates. Hardness minerals like magnesium and calcium result in the buildup of hardened limescale. Accumulation of limescale can reduce the efficiency of the distiller or even cause total damage.
Regular cleaning of a water distiller also prevents the growth of organisms such as bacteria and mold. Apart from routine cleaning practices, it's important to rinse the boiling chamber in between distillation cycles to remove residue and maintain the efficiency of the distiller.
When selecting a water distiller, start by considering your capacity needs. Choose a water distiller that matches your daily volume requirements. Volume output can be impacted by the distiller's gross capacity or its distillation speed. Either way, ensure your distiller can produce enough pure water without sacrificing efficiency.
Another thing to consider is the quality. Generally, stainless steel water distillers are the most durable. Food-grade 304 stainless steel is one of the best materials for making the interior of water distillers. Apart from great build quality, opt for distillers that offer warranty services for their customers.
Perhaps the most important factor that will determine your choice of a water distiller is the cost. For simple home use for an average family, a countertop water distiller with a capacity of about 5 liters can suffice, and these are more affordable. Long-term costs can be cushioned by selecting a water distiller with a higher energy efficiency rating.
Aside from the basic features, some water distillers have additional unique features that may influence your decision. Some brands add features such as self-sterilization, water quality monitoring, and automatic shut-off. If these brands are within your price range, it's worth considering these additional features.
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