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Water color

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Water color is one of the water quality characteristics that can be easily assessed visually. This applies to the water from the centralized water supply system as well as the water from wells and other sources. In apartment buildings the water in orange or even brown color often flows through the tap. In the warm summer season water in green color is observed in many places. But researchers and vacationers often are visiting places around the world where the water bodies are colored in a unique colors (most often blue, greenish-blue or emerald green).

What affects the color of the water and why the water stains in one or in another shade? Those are the topics we will discuss in this article.

What affects the color of water?

The color of the water can be influenced by a large number of factors, however, main ones are:

  1. Water impurities such as iron, manganese and other mineral salts of metals which can give color to the water. Depending on their content the colors may vary.
  2. Microorganisms that are living in the water also have their own color and are able to stain water in different colors.
  3. Solar activity which is the main reason for the blue color of the water.
  4. The depth of the water bodies.
  5. The bottom of the water body.


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The main reason for the yellowish tint of the water is the iron dissolved in it. This can be easily examined: the water in the well is clear at first but when it comes into contact with air it turns yellow. If the iron content in the water is very high, it is also possible to observe a sediment in a darker color (brown, red). As a source of iron for tap water can also be worn-out pipelines. When you stop the water supply and later restore it you can see that the water from the faucet has an orange color.

Iron in drinking water can be found in three forms:

  • in dissolved form: the water is clear;
  • in precipitated form: the water is cloudy, rust-colored;
  • in colloidal form: iron associated with organic impurities characterized by a yellowish color.

Another reason for the yellow color of the water may be humic substances that are present in water intake points and are not completely destroyed during centralized treatment. Humic substances (humic and fulvic acids) occur in the process of decomposition of organic residues, they are the basis of the plant nutrition chain and affects soil fertility.


Green color in the water most likely characterizes the development of blue-green algae in it. With an increase in the water temperature and the level of pollution they begin to actively multiply and change the color of the water. The water becomes cloudy and the body of water gradually becomes covered with mucus. This process is called “overgrowth of water bodies” or “water blooming“. This process can most often be observed in stagnant water bodies (for example in lakes and ponds) where there is no active water exchange. This is facilitated by warm weather without wind when the water temperature is above 16° C and the water contains sufficient nutrients (e.g. nitrogen and phosphorus compounds).

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The brown color of the water is created by biological processes such as decay in swamps. Rarely brown or red color is created by mineral salts, as, for example, iron compounds.

A good example in this case are artificial salt ponds in San Francisco (USA), which are used to obtain salt. In different areas of the water bodies live different colonies of microorganisms that “help” in the technological process. Colonies of green and blue microorganisms are observed in areas with sweeter water while in areas with saltier water brown and red tones are observed.

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In Japan the water in the lake “Bloody Pond” is saturated with iron salts and due to the proximity of the volcano, its temperature reaches 90°C.

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Milk-colored water can have two sources:

  • dissolved oxygen;
  • pollution from industrial wastewater.

When water quickly moves along the mountain rivers or falls into waterfalls, it is saturated with many small air bubbles and turns white. As for industrial sewage, they may contain a large amount of white suspended matter, thereby making the water cloudy.

The color of the water depending on the time of day and weather conditions

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The blue color of the water is due to the reflection of the sky in the water. At sunset the water that was blue can reflect red color or even turn black. During a storm the color of the water bodies turns gray as the sky has the same shade. The optical effects of water are also explained by the dependence of the saturation of the color and the depth of the water body.

What is at the bottom?

Great importance in what color the surface of the water will be is also played by the bottom layer of rivers, lakes and seas. If the bed of the water body is covered with algae, then the water will be dark. If the bed is covered with light limestone stones or sand, then the water will be blue.

A good example of how the composition of bottom sediments affects the color of water is the three adjacent Kelimutu lakes in Indonesia which have different colors.

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Unusual water reservoirs in Latvia

Unusual and beautiful water bodies in different colors can be found not only in the USA, Japan or Indonesia but also in Latvia.

1. Lake Lāčkrogs

In Kurzeme near Renda there is located lake Lāčkrogs. It is formed on the site of a lime quarry and has acquired its magnificent color due to this rocks. Photographer Egons Lācis describes lake Lāčkrogs as “Clear blue as in the Mediterranean Sea!”.

2. Lake Velnezers

In the Graveru forest 12 km from Aglona there is located lake Velnezers which is also called Chertok, Čortok or Chertak. In the middle of the blueberry forest visitors are delighted with this lake with clear water of emerald-green color. The transparency of water in some places is even 12 meters.

3. Reservoir Ruģeļi

Untypical greenish-blue water can be found in the Rugeli reservoir which is located 4 km from the center of Daugavpils. This body of the water was created in preparation for the construction of the Daugavpils hydro electric station. Depending on weather conditions the watershed changes its color revealing even the exotic greenish-blue color.

4.Dubkalni quarry 

On the territory of the nature park “Ogre Blue Mountains” there is a water reservoir of Dubkalni. Thanks to the fact that there are many underground springs on the territory of the park, the water is clean and crystal clear.

Read also: The smell and taste of the water. 



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