What are the 7 types of water?

Water comes in many different forms and types. While we are familiar with the water we drink and bathe in every day, there are actually 7 main types of water found on Earth. Each type has its own unique properties and uses. Understanding the different types of water can help us better appreciate this precious resource.

1. Freshwater

Freshwater is the most common type of water that we encounter. It has a low concentration of dissolved salts, making it suitable for drinking and irrigation. Freshwater is renewed through the water cycle, where water evaporates from oceans, condenses into clouds, and falls back down to Earth as rain or snow.

Sources of freshwater include:

  • Surface water from lakes, rivers, and streams
  • Underground water from aquifers and wells
  • Precipitation like rain and snow

Freshwater makes up only about 3% of the total water on Earth. Of this, 30% is groundwater, while the remaining 70% is frozen in glaciers, ice caps, and permanent snow.

Uses of Freshwater

Freshwater has many vital uses including:

  • Drinking – Freshwater is essential for all living organisms to survive
  • Agriculture – Used for crop and livestock irrigation
  • Industry – Used as a raw material and for processing and cooling in many industries
  • Electricity – Hydropower generation uses flowing freshwater like rivers to produce electricity
  • Transportation – Allows for shipping routes along internal waterways
  • Recreation – Used for swimming, fishing, boating, and other recreational activities

2. Saline Water

Saline water contains a significant concentration of dissolved salts. Seawater is a type of saline water, with an average salt content of around 3.5%. Saline water can originate from the oceans, chemical brines, and saline groundwater.

Uses of Saline Water

Some uses of saline water include:

  • Aquaculture – Used to fill fish farms and hatcheries
  • Desalination – Removing salt from saline water produces freshwater for drinking and agriculture
  • Oil and gas production – Saline water is sometimes extracted with oil and gas and re-injected into wells
  • Chemical extraction – Valuable elements like lithium can be extracted from saline water

3. Hard Water

Hard water contains high levels of dissolved minerals like calcium and magnesium. It gets its name because it feels hard and sticky due to the extra minerals. Hard water forms when freshwater flows through and dissolves rocks and sediment that contain calcium and magnesium.

The main impacts of hard water include:

  • Reduced lathering of soap
  • Scale buildup in pipes and appliances
  • Mineral spots on dishes

Water hardness is measured in grains per gallon (gpg) or milligrams per liter (mg/L). The following classifications are used:

Classification Grains per gallon (gpg) Milligrams per liter (mg/L)
Soft 0-3.5 0-60
Moderately hard 3.5-7 61-120
Hard 7-10.5 121-180
Very hard Over 10.5 Over 180

Treating Hard Water

There are several options for treating hard water to reduce mineral content:

  • Water softeners – Ion exchange process that replaces calcium and magnesium with sodium
  • Reverse osmosis – Pressurized system that pushes water through a membrane, filtering out minerals
  • Distillation – Removes minerals by boiling and condensing water
  • Mineral precipitating filters – Use a chemical reaction to turn dissolved minerals into an insoluble solid

4. Soft Water

Soft water has low concentrations of ions like calcium and magnesium. It has properties opposite of hard water. Soft water feels slippery, produces more lather, and prevents scale buildup.

Rainwater is naturally soft water, as it doesn’t come into contact with minerals to become hard. Water softening processes like ion exchange produce artificial soft water by removing minerals.

Benefits of Soft Water

  • Forms more bubbles and lather with soap and detergent
  • Leaves no mineral spots on dishes, fixtures, or appliances
  • Prevents scale buildup from hard water salts
  • Makes hair and skin feel smoother

5. Distilled Water

Distilled water is created through distillation, which involves boiling water and condensing the steam. This leaves behind a water with nearly all impurities and minerals removed. Distilled water’s purity gives it a flat, neutral taste.

Uses of Distilled Water

  • Medical equipment sterilization
  • Laboratory experiments and testing
  • Steam irons and humidifiers
  • Automotive batteries
  • Vodka, whiskey, and gin production

However, the lack of minerals makes distilled water a poor choice for drinking water. The flat, mineral-free taste is unappealing and it can lead to mineral depletion over time.

6. Heavy Water

Heavy water contains a heavier form of hydrogen called deuterium. The chemical symbol for heavy water is D2O, compared to normal light water, H2O. Heavy water gets its name because deuterium forms a water molecule about 10% denser than normal.

Only about 0.0156% of natural water is heavy water. Heavy water for industrial uses is produced through a process called water distillation.

Uses of Heavy Water

  • Nuclear reactors – Used as a neutron moderator
  • Scientific research – Useful for studies on metabolism and neuromuscular functioning
  • pH measurement – Used as a standard for the pH scale

7. Mineral Water

Mineral water comes from underground reservoirs and contains at least 250 parts per million of total dissolved mineral salts. Compared to spring water which has lower mineral content, mineral water picks up more minerals from aquifers.

Mineral water contains essential elements like calcium, magnesium, sodium, potassium, and iron. However, mineral content can vary widely between different mineral water brands.

Uses of Mineral Water

  • Direct drinking
  • Carbonated beverages like sparkling mineral water
  • Enhanced flavor of foods
  • Nutrient supplementation

Mineral water is valued for supposed therapeutic health benefits, though these are scientifically debated. More research is needed to understand how the mineral content impacts human health.


Freshwater, saline water, hard water, soft water, distilled water, heavy water, and mineral water represent the 7 major types of water. Each type has distinct properties based on its mineral content and how it was formed or processed.

Understanding the different water types helps us appreciate water’s incredible diversity. We can better manage our water resources by considering the unique benefits and applications of each kind of water.

Water supports all life on Earth – having clean, usable water is crucial. We must protect the health of freshwater ecosystems and use our available water sustainably. With environmental challenges like drought, pollution, and climate change, a thorough understanding of water resources becomes increasingly important.

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