What Exactly is Purified Drinking Water?

January 12, 2026 •

4 min read

According to the World Health Organization, over 2.1 billion people lack access to a safe, readily available water supply. Purified drinking water undergoes advanced treatment processes to remove impurities and contaminants, making it exceptionally clean and safe for consumption.

Quick Summary

Purified water is treated to remove impurities and contaminants, often surpassing municipal tap water standards. Common methods include reverse osmosis, distillation, and deionization, resulting in a cleaner, safer water source. It differs from simple filtered water by its more comprehensive removal of contaminants like chemicals and microbes.

Key Points

Definition: Purified drinking water is mechanically treated water, often using methods like reverse osmosis or distillation, to remove contaminants and chemicals for a higher level of purity.
Purity Standards: For water to be considered 'purified,' it must typically have a total dissolved solids (TDS) level of less than 10 parts per million (PPM).
Purification Methods: Key techniques include reverse osmosis (forcing water through a semi-permeable membrane), distillation (boiling and condensing steam), deionization (removing mineral ions), and UV disinfection (killing microorganisms with light).
Health Benefits: Drinking purified water can reduce exposure to harmful contaminants like chlorine and lead, potentially improving overall health and hydration.
Important Distinction: Purified water is different from filtered water. Filtering removes larger particles and some chemicals, while purification is a more comprehensive process that removes almost all impurities.
Home Options: Purified water can be obtained through point-of-use systems (under-sink filters), buying bottled varieties, or using countertop distillation units.
Mineral Content: Some purification methods, like distillation and reverse osmosis, remove beneficial minerals. Some systems add minerals back for taste and health.

Understanding the Concept of Purified Water

Purified water is water from any source that has been mechanically processed to remove chemical pollutants, bacteria, and other contaminants, producing a higher quality of water than what is considered potable tap water. Unlike basic filtration, which might only remove suspended solids, purification involves a more intensive, multi-stage process designed to strip the water of virtually all impurities. The final product must meet strict quality standards, typically with a total dissolved solids (TDS) measurement of less than 10 parts per million (PPM).

The Need for Water Purification

Even in countries with strict municipal water regulations, tap water can contain traces of contaminants. These can include chemicals used for disinfection, such as chlorine, along with heavy metals like lead and copper that can leach from aging pipes. For individuals with compromised immune systems, children, or those simply seeking a higher level of water quality, opting for purified water provides extra assurance of safety. Beyond safety, the removal of impurities also results in better-tasting water, free from the chemical odors often associated with tap water.

Common Methods for Purifying Water

Several advanced techniques are used to produce purified water, often in combination to achieve the highest possible purity.

1. Reverse Osmosis (RO)

This method uses mechanical pressure to force water through a semi-permeable membrane, which has tiny pores that block the passage of most dissolved inorganic solids, heavy metals, and microorganisms. RO is highly effective at removing a wide array of contaminants but also removes beneficial minerals. Some RO systems include a remineralization stage to add back healthy minerals.

2. Distillation

Distillation involves boiling water and then collecting and condensing the resulting steam back into a clean container. Since most contaminants have higher boiling points than water, they are left behind in the boiling vessel. This process produces very pure water, but it is energy-intensive and also removes all minerals, which can result in a flat taste.

3. Deionization (DI)

Deionization, or demineralization, removes mineral ions (salts) from water through a chemical ion-exchange process. Water passes through special resins that trade hydrogen and hydroxide ions for dissolved mineral ions. While effective at removing salts, it does not remove uncharged organic molecules, viruses, or bacteria. For drinking purposes, DI water is often used in combination with other methods.

4. Ultraviolet (UV) Disinfection

UV purification uses ultraviolet light to destroy the DNA of microorganisms like bacteria and viruses, rendering them harmless. It is a highly effective, chemical-free disinfection method but does not remove other contaminants, such as chemicals or dissolved solids. It is typically used as a final stage of purification after other methods have removed larger particles.

Purified vs. Other Types of Water: A Comparison


Feature	Purified Water	Filtered Water	Tap Water
Purity Level	Very high, typically <10 ppm TDS.	Varies, depends on the filter type; less thorough than purification.	Varies by municipality; meets minimum federal/state standards but may contain residual contaminants.
Contaminants Removed	Most chemicals, heavy metals, bacteria, viruses, and dissolved solids.	Chlorine, sediment, and some contaminants, but not all bacteria, viruses, or dissolved solids.	Some contaminants removed during municipal treatment, but may contain residual chemicals and leachates from pipes.
Taste	Often described as clean and neutral.	Can be improved by removing chlorine, but depends on raw water quality.	Varies greatly depending on location and treatment.
Common Methods	Reverse Osmosis, Distillation, Deionization, UV.	Activated Carbon, Sediment Filters.	Municipal processes including coagulation, flocculation, sedimentation, and disinfection.
Mineral Content	Can be low, depending on the method (e.g., distillation).	Retains most natural minerals.	Varies, can be a source of some minerals like calcium and magnesium.

How to Get Purified Water at Home

For those seeking the benefits of purified water, several options are available for home use.

Point-of-Use (POU) Systems: These are small, localized units that purify water used for consumption, such as under-sink filters or countertop units. RO and multi-stage filter systems are popular POU choices.
Bottled Purified Water: Buying bottled purified water is convenient but can be more expensive and has a significant environmental impact due to plastic waste.
Water Distillers: These countertop appliances boil and condense water, but the process can be slow and energy-intensive.

Conclusion: Making an Informed Choice

What exactly is purified drinking water depends on the advanced treatment it receives, distinguishing it from basic filtered or standard tap water. It offers a solution for those concerned about contaminants, providing cleaner, safer, and better-tasting water. While tap water is deemed safe in many areas, factors like local water quality, aging infrastructure, and individual health needs may lead people to seek a higher standard. Choosing purified water, through either a home system or bottled varieties, is a personal decision that can significantly impact your health and daily water intake. An informed choice ensures you and your family are properly hydrated with the highest quality water available to you.

An excellent resource for learning about water quality is the U.S. Environmental Protection Agency website, which provides information on drinking water regulations and safety standards.

Frequently Asked Questions

Filtered water passes through a filter, like activated carbon, to remove some contaminants such as chlorine and sediment. Purified water undergoes a more rigorous, multi-stage process (like reverse osmosis or distillation) to remove nearly all inorganic solids, chemicals, and microbes.

Yes, purified water is generally considered safe for daily consumption. The main consideration is that some purification methods remove beneficial minerals, so a balanced diet is important to compensate.

Purified water effectively removes chemicals (e.g., chlorine, pesticides), heavy metals (e.g., lead, copper), bacteria, viruses, parasites, and other dissolved solids.

Yes, some purification methods, especially distillation and reverse osmosis, remove both harmful contaminants and beneficial minerals like calcium and magnesium. Some modern purifiers add these minerals back.

In many developed areas, tap water is safe. However, purified water undergoes extra treatment, removing more contaminants that may remain in tap water due to local source issues or aging pipes. Whether it is 'better' depends on your local water quality and personal preference.

You can get purified water at home through systems like reverse osmosis units (often installed under the sink), water distillers, or by buying bottled purified water.

Water that has been purified by distillation or reverse osmosis can sometimes taste 'flat' because the process removes all dissolved minerals, which can affect the taste. Some systems re-mineralize the water to improve flavor.