Water's organoleptic properties include odor, taste (aftertaste), turbidity, and color. In this article, we will focus on taste and odor. Although they are primarily aesthetic factors, they can indirectly indicate the presence of certain pollutants in the water. Water's odors and tastes are indicative of the content of certain substances that cause these phenomena, such as dissolved salts, various chemical and organic compounds. It is important to note that these parameters are evaluated on a five-point scale, which is outlined in the table below.
It is worth noting that odors are evaluated for water of any origin; however, this determination is not made for water that is known to be contaminated with harmful impurities.
ASSESSMENT OF WATER ODORS AND TASTES
WHY DOES WATER HAVE AN UNPLEASANT SMELL AND HOW TO DEAL WITH IT?
ODOR OF ROTTEN, FISHY OR EARTHY
Most commonly found in water from open reservoirs. Caused by the presence of natural organic compounds in the water. The most well-known of these natural compounds are geosmin and 2-methylisoborneol. These compounds are usually safe for humans, although they can sometimes be caused by the presence of blue-green algae and bacteria in the water. Water is most strongly enriched with these compounds during the flowering period of reservoirs.
Occurs mainly in the central water supply system. Caused by strong chlorination of water at municipal treatment plants.
SMELL OF ROTTEN EGGS
The presence of dissolved hydrogen sulfide (H2S) in the water. Less commonly, the presence of sulfide bacteria that produce hydrogen sulfide. Tap water smells like rotten eggs if it comes directly from a well without further purification.
Removal: Centaur filters (activated carbon - catalytic oxidation and adsorption) or MGS (green sand filter with manganese). Chlorination of water is necessary to remove bacteria.
CHEMICAL AND PHENOLIC ODOR
This type of odor is caused by the entry of wastewater into the water supply system or into the aquifer (in the case of groundwater abstraction).
Removal: activated carbon filter (adsorption).SALTY TASTE
Caused by elevated levels of salts in the water: NaCl, NaSO4, MgSO4.
Indicates an increased content of iron and/or manganese in the water. At very high concentrations, the water from the tap has a smell of an iron.
Removal: complex purification systems with Ecomix, BIRM, MGS, and other iron removal methods.
Caused by a high pH level in the water.
The table below provides a more detailed classification of odors with an indication of their origin.