Understanding Water Taste and Odor: Causes, Effects, and Solutions

Organoleptic properties of water include indicators such as odor, taste (flavor), turbidity, and color. In this material, we will discuss taste and odor. In addition to being critical for aesthetic aspects, they can indirectly indicate the presence of certain contaminants in the water. Odors and flavors in water are signs of the presence of specific substances, such as dissolved salts and various chemical and organic compounds. It is important to note that these parameters are evaluated using a five-point scale, as detailed in the table below.

It is worth noting that the evaluation of odors is conducted for water of any origin. For water that is known to be contaminated with harmful impurities, such an assessment is not performed.

Assessment of water odors and flavors

Score	Odor and Flavor Intensity	Description of Intensity
0	None	Absence of any detectable odor or flavor.
1	Very Weak	Odor or flavor that is undetectable by the consumer but identified in the laboratory by an experienced analyst.
2	Weak	Odor or flavor that does not attract the consumer's attention but can be detected if noticed.
3	Noticeable	Odor or flavor that is easily noticeable and may cause a negative perception of the water.
4	Clear	Odor or flavor that draws attention and makes the water unpleasant to drink.
5	Very Strong	Odor or flavor that is so strong that it renders the water unsuitable for drinking.

Why Does Water Have an Unpleasant Odor and How to Deal with It?

Rotten, Fishy, or Earthy Odor‍

This odor is most commonly found in water from open water sources. It is caused by the presence of natural organic compounds in the water, such as geosmin and 2-methylisoborneol. These compounds are generally safe for humans, although they can sometimes be related to the presence of blue-green algae and bacteria in the water. The concentration of these compounds is highest during algal blooms.

Removal: Activated carbon filters (adsorption); for drinking water - household reverse osmosis.

Chlorine Odor
This odor is mainly found in municipal tap water. It is caused by the heavy chlorination of water at urban treatment plants.

Removal: Activated carbon filters (adsorption); for drinking water - household reverse osmosis, triple filters, and pitchers.

Sulfur Odor (Rotten Eggs)

‍The presence of dissolved hydrogen sulfide (H2S) in the water. Less commonly, it may be caused by sulfide bacteria that produce hydrogen sulfide. Water from wells without further treatment can smell like rotten eggs.

Removal: Filters with Centaur loading (activated carbon - catalytic oxidation and adsorption) or MGS (manganese green sand). Chlorination of water is necessary to remove bacteria.

Chemical or Phenolic Odor

This type of odor is caused by the presence of wastewater in the water supply system or in the groundwater (in the case of extraction from underground sources).

Removal: Activated carbon filters (adsorption).

Types of Unusual Tastes in Water and How to Remove Them

Water can have various recognizable tastes for different reasons. It is always important to identify the cause of a specific taste or odor before choosing methods for its removal. Filtration, changing the water source, or treatment can be effective methods for improving water quality.

Salty Taste

Caused by an increased content of salts in the water: NaCl, NaSO4, MgSO4.

Removal: Desalination (deionization or reverse osmosis). For drinking - household reverse osmosis.

Metallic Taste

Indicates an increased content of iron and/or manganese in the water. At very high concentrations, tap water may smell like iron.

Removal: Comprehensive treatment systems with Ecomix, BIRM, MGS, and other iron removal methods.

Alkaline Taste

Caused by a high alkalinity level in the water.

Removal: Reverse osmosis or deionization systems (N-cationization). For drinking - household reverse osmosis.

The table below provides a more detailed classification of odors with their origins.

Characteristics of All Tastes and Odors

Characteristics of Taste or Odor
Tastes Without Odors
Salty	Water with a salty taste often contains sodium chloride (table salt).
Bitter	Magnesium sulfate or sodium sulfate.
Bitter, Astringent	Iron and aluminum sulfates, excess lime.
Bitter, Metallic	Water with a metallic taste usually contains iron sulfates, manganese, and copper.
Soapy	Sodium carbonate (soda).
Sweetish	Sodium bicarbonate (baking soda).
Peaty or Plant-like	Humic acids.
Tasteless, Flat (Weak)	Lack of dissolved oxygen, hardness salts, and high temperature (warm water).
Astringent, Irritating, Causes Tickling and Dryness in the Mouth	Presence of styrene - this water cannot be used for drinking.
Odors Without Tastes
Hydrogen Sulfide	Hydrogen sulfide in well water.
Petroleum and Paraffin	Presence of petroleum products in the water, which may be of natural or industrial origin.
Tastes in Combination with Odors, Natural or Existing Before Treatment
Earthy	Activity of actinomycetes in river water, particularly common during flood periods.
Geranium, Violet, Cucumber, Nasturtium, Fishy, Swine	Indicate algal growth in the water body.
Weedy, Earthy, Herbaceous, Musty, Moldy, Rotting Plants	Decay of plants in water bodies or in structures.
Phenolic, Aromatic, Chemical Products	Water with a sour taste and chemical reagent notes usually contains industrial wastewater pollutants.
Tastes and Odors Acquired as a Result of Water Treatment
Moldy	Formed as a result of chlorinating water rich in algae.
Chlorophenolic (Medicinal), Iodoform, Chemical Goods	Result of chlorinating water containing industrial wastewater.
Chlorine Odor	Chlorination of relatively clean water.
Tastes and Odors Arising in Pipelines
Resinous, Naphthalene	Leaching of resinous substances in new pipelines and other structures.
Creosote, Fishy	Result of pollution by industrial wastewater.
Tasteless, Flat	Formed from prolonged standing of water in tanks and containers.
Musty	Often results from the proximity of hot and cold pipelines.
Unpleasant Taste and Rotten, Plant-like Odor	Indicates the proliferation of hydrobionts in tanks and other water supply structures.

Resources:‍

Jewell, Tim. 2019. Water’s Flavor and Where It Comes From. healthline.com/health/does-water-have-a-taste (6 Desember 2019).
Wisialowski, Kate. March 18, 2018. The Drinking Water Taste Guide.

It is worth noting that the evaluation of odors is conducted for water of any origin. For water that is known to be contaminated with harmful impurities, such an assessment is not performed.

Assessment of water odors and flavors

Score	Odor and Flavor Intensity	Description of Intensity
0	None	Absence of any detectable odor or flavor.
1	Very Weak	Odor or flavor that is undetectable by the consumer but identified in the laboratory by an experienced analyst.
2	Weak	Odor or flavor that does not attract the consumer's attention but can be detected if noticed.
3	Noticeable	Odor or flavor that is easily noticeable and may cause a negative perception of the water.
4	Clear	Odor or flavor that draws attention and makes the water unpleasant to drink.
5	Very Strong	Odor or flavor that is so strong that it renders the water unsuitable for drinking.