Optimal water intake is essential for your health.
Every cell in your body needs water to function properly, which is why you must continuously hydrate throughout the day.
Most people know how important water intake is, but some are confused over the best type of water to drink.
This article investigates the differences between purified, distilled and regular water to find out which one is the best choice for hydration.
Purified water is water that has been filtered or processed to remove impurities like chemicals and other contaminants.
It is usually produced using groundwater or tap water.
Through purification, many types of impurities are removed, including (1):
- Metals like copper and lead
- Chemical pollutants
Several methods are used to purify water commercially and in the home.
In most Western countries, public drinking water is purified to make water safe for human consumption.
However, standards for drinking water around the world vary and are typically based on governmental regulations or international standards.
In fact, the World Health Organization estimates that over 2.1 billion people lack access to safe drinking water (2).
In countries that purify public drinking water, various treatment methods are used to make water safe, including (3):
- Coagulation and flocculation: Positively charged chemicals are added to water to bind with negatively charged particles so they can be filtered out. This forms larger particles called floc.
- Sedimentation: Due to its larger size, floc settles to the bottom of the water supply, separated from the clean water.
- Filtration: The clean water on top of the supply then flows through numerous filtration systems made of sand, charcoal and gravel. This removes contaminants like dust, bacteria, chemicals and viruses.
- Disinfection: During this step, chemical disinfectants like chlorine are added to the water to kill any remaining bacteria or viruses that may have survived the first few steps.
It’s important to note that water may be treated differently depending on the area and quality of the local water.
Summary: Purified water is water that has been processed to remove contaminants like dirt and chemicals. In many countries, tap water is purified to make it safe for human consumption.
While tap water is safe to drink in many areas, it may still contain trace contaminants.
For example, the US Environmental Protection Agency (EPA) sets legal limits that are considered safe for consumers for over 90 contaminants in drinking water (4).
However, the Safe Water Drinking Act gives individual states the ability to regulate their own drinking water standards, as long as they meet the EPA’s minimum requirements for contaminants (5).
This means that some states have more stringent drinking water regulations than others.
Although measures are taken to ensure that public drinking water is safe for consumption, it can contain trace amounts of contaminants that could negatively impact health.
These heavy metals have been known to leach into drinking water, even in countries where public water sources are closely regulated (8).
By using in-home water filters or drinking purified bottled water, drinking water undergoes another level of purification that can remove metals, chemicals and other contaminants, depending on the type of purification system used.
Water purification systems like charcoal filters remove chlorine, a common chemical added to the public water supply as a disinfectant.
Another benefit of water purification is that it removes unpleasant tastes associated with chemical treatments, organic matter or metal plumbing, leaving you with fresh, pure-tasting drinking water.
Summary: Water purification removes contaminants that may remain in drinking water and improves water quality and taste.
While purified water has many health benefits, it also has some potential drawbacks.
For example, fluoride is a mineral that is added to public drinking water supplies in some countries to improve dental health and reduce dental decay (11).
Although this practice has led to decreased tooth decay in children, especially in at-risk areas, some argue that fluoridated water is not worth the potential health risks associated with its use.
Excessive fluoride levels can be toxic to both brain and nerve cells, and long-term exposure to high levels of fluoride has been linked to learning, memory and cognitive deficits (12).
However, experts argue that the level of fluoride found in drinking water is safe and beneficial in reducing tooth decay, especially in children who are only exposed to fluoride through drinking water (13).
Research on the safety and efficacy of fluoridated water is ongoing, but those who drink purified water should be aware that some purification systems remove fluoride from drinking water.
Some other disadvantages of purified water include:
- Upkeep: Water purification systems must be maintained regularly. If not properly maintained, contaminants can build up in old filters and leach into your drinking water.
- May not remove some contaminants: Although water purification systems remove many contaminants, certain pesticides and chemicals may remain in purified water depending on the type of purification used.
- Cost: Both installing an in-home water purification system and buying purified bottled water can be expensive, with some systems costing hundreds of dollars.
- Waste: Buying purified water in plastic bottles leads to a large amount of waste, as does disposing of used filters from in-home purification systems.
Summary: Water purification may not remove all contaminants from drinking water, and certain purification systems can be costly and involve upkeep. Certain purification methods remove fluoride, a mineral added to drinking water to improve dental health.
Distilled water has gone through the process of distillation to remove impurities.
Distillation involves boiling water and collecting the steam, which returns to water upon cooling.
This process is very effective at removing contaminants like bacteria, viruses, protozoa like giardia and chemicals like lead and sulfate (14).
Due to the fact that distilled water is exceptionally pure, it is commonly used in medical facilities and laboratories.
Though drinking distilled water is not as common as drinking other types of purified water, some people choose to drink it because it is free of contaminants.
Benefits of Distilled Water
Water distillation is an effective way to remove contaminants from drinking water.
Levels of pesticides and other chemicals in public water sources like tap water will depend on your geographic location and the agencies that regulate drinking water safety in your country.
Distilled water is essentially free of contaminants like pesticides and bacteria, which could be especially helpful to those with weakened immune systems.
For example, those with HIV/AIDS and certain cancers are at an increased risk of becoming sick from impurities in food and water and may benefit from drinking distilled water (15).
What’s more, like some other purification methods, distilled water effectively removes chlorine from drinking water, which can improve the taste of water while decreasing your exposure to chlorine.
Potential Risks of Distilled Water
While distilled water is the purest type of water, it’s not necessarily healthiest.
The distillation process is very effective at removing potentially harmful contaminants, but it also removes the natural minerals and electrolytes found in water.
Along with unwanted impurities, beneficial minerals like calcium and magnesium are also left behind as the steam rises during the distillation process.
In fact, distillation typically removes around 99.9% of all minerals found in tap water (16).
Though water is not typically thought of as a source of minerals, any factor that leads to a decreased intake of essential micronutrients could negatively impact your health.
However, it’s important to note that tap water is not a major source of mineral intake for most people, and drinking distilled water should be relatively safe as long as a well-balanced diet is followed.
Like other methods of purification, distillation removes fluoride from drinking water, which may put those who choose to drink distilled water at an increased risk of cavities.
This makes it important for those who drink distilled water to maintain proper dental hygiene.
Summary: Distilled water is a type of purified water that is essentially free from contaminants. The distillation process removes fluoride and natural minerals found in drinking water.
In most cases, public drinking water sources like tap water are safe due to the strict contaminant limits set by regulatory agencies.
However, drinking water can become contaminated from natural sources or human activity, affecting water quality (19).
For this reason, it may be a good idea to invest in an in-home water purification system, especially those who are immunocompromised and more susceptible to becoming ill from contaminated water.
In countries where water contamination is an issue, especially in developing countries with lack of proper sanitation, choosing bottled or purified water is always the safest option.
Many types of purification systems are available, including charcoal and UV filters, which remove impurities that may survive the initial, large-scale purification process that most tap water goes through.
That being said, in countries where public drinking water is regulated for quality and safety, drinking tap water is relatively safe.
If you question the quality of your tap water, you can test the water by purchasing a home test kit or contacting a water testing agency in your area.
Summary: Though consuming tap water is safe in countries where drinking water is regulated, water purification may be necessary in areas where water contamination is an issue.
Most public sources of drinking water are regulated for safety, but some people choose to use home water purifiers to further improve water quality.
Household water treatment units can improve the taste or odor of tap water and remove specific contaminants.
Point-of-use (POU) treatment systems purify only the water that is used for consumption (drinking and cooking). Point-of-entry (PUE) treatment systems typically treat all of the water entering a home (20).
POU systems are less expensive and therefore more commonly used in households.
These filtration systems attach to the faucet or sit under the sink and also come in free-standing water pitchers with built-in filters like the popular Brita water filter.
Some refrigerators also come with built-in water purification systems.
Most in-home water filtration systems use the following purification techniques (21):
- Filtration: Filtration systems trap unwanted impurities in the surface or pores of an absorbent medium. Charcoal filters fall into this category.
- Reverse osmosis: These systems use a semipermeable membrane that removes impurities.
- UV light: UV light filtration systems use ultraviolet light to disinfect water by killing potentially harmful bacteria and viruses.
Depending on the type and model, prices can range from $20 to hundreds of dollars.
No matter what type of filter you choose, be sure to look for brands with certifications from regulatory agencies like the American National Standards Institute (ANSI) and NSF International.
These agencies certify that home water purification systems meet or exceed national drinking water standards (22).
Home water purification systems must be maintained properly. As a result, it’s important to follow the manufacturer's recommendations for upkeep, including filter replacement, to ensure that your water is being properly purified.
Summary: There are many ways to purify your drinking water, including charcoal filters, UV light filtration systems and reverse osmosis systems.
Access to clean drinking water is vital to health.
While most sources of public drinking water are closely regulated and safe to drink, many prefer to drink purified water.
Purified water is relatively safe and may reduce exposure to certain contaminants that can be found in tap water.
Remember that water quality can vary depending on where you live. This should be the determining factor when choosing to drink purified water or tap water.