Causes of smelly drinking water

1. The taste of water

The taste of water is generally the initial feeling of water. It should be noted that the senses are only people’s intuitive feelings about the appearance of drinking water, not the internal quality, so water with good senses does not mean that it is safe; at the same time, water with poor senses is not necessarily unsafe. Therefore, the quality of water quality cannot be judged simply by the taste of water. For the same person, different water quality will bring different tastes; but due to individual differences (different sense of smell and taste sensitivity), the same water will also bring different feelings to different people. Especially taste, it is closely related to the region where people grow up, age, physical condition and eating habits. Water temperature is also one of the important factors in determining whether water is delicious. When the water temperature is around 20°C, it is generally considered to be delicious. If the water temperature is too low, it will make people feel sluggish, but in hot weather, very cold water makes people also It feels good to drink. That is to say, with the change of climatic conditions and the adjustment function of the human body, people’s perception of water taste will also change. Quality drinking water means good and safe water. Humans are inseparable from water, and safe drinking water is an important guarantee for human life and health.

2. Water quality and taste

Water that is completely free of impurities is not delicious. The taste of water is determined by water and other components. Other components in water have two meanings, one is the natural ingredients and their content, and the other is the substances they contain and their content after being polluted.

Among the natural components of water, the main factors that affect the taste of water are as follows:

  1. Total dissolved solids: Refers to the total amount of solid substances contained in water that can be dissolved in water, also known as evaporation residues, including calcium, magnesium, sodium, potassium and other minerals and chloride ions, carbonates, silicates, sulfuric acid roots and some organic matter, etc. For example, when there are too many MgCl2 and CaCl2, the water will be bitter.
  2. Chloride ion: The content of chloride ion is too high, and it has the same taste as salt. Groundwater in coastal areas is not drinkable, often due to seawater intrusion or over-exploitation of groundwater, and the chloride ion content is too high, making it unsuitable for drinking. GB5749 stipulates that the chloride in drinking water should be lower than 250mg/L. For example, when the NaCl content is greater than 100mg/L, people with sensitive taste already feel salty, and when it reaches 250mg/L, most people feel salty.
  3. Sulfate: Sulfate is common in natural water, and when its content is high, the water will have an astringent taste. Most people feel a laxative effect when sulfate is too high.
  4. Carbonate: Carbonic acid is carbon dioxide dissolved in water. Carbonate is present, which gives the water a refreshing and delicious taste. If the content is too high, the water taste will be irritating, resulting in the feeling of soda, so that the water will lose its proper taste. 1. Hardness: In clean water, the content of calcium, sodium, and magnesium ions is much higher than that of other types (potassium, zinc, strontium, etc.). Converting calcium and magnesium into calcium carbonate concentration is the hardness of water. If the hardness is too high, the taste is not good and there is peculiar smell, and individual drinkers will also have gastrointestinal reactions; if the hardness is too low, the water will not be sweet. my country stipulates that the total hardness of drinking water is less than 450mg/L.
  5. Silicate: Silicate is a component that dissolves in water from rocks, especially volcanic rocks are more likely to dissolve silicates. The concentration of silicates in natural water is high, and it feels a bit hard when drinking water. Shenyang activated carbon filter, Shenyang water purifier
  6. Residual chlorine: Residual chlorine is the chlorine remaining in the water when using chlorine-containing disinfectants, and has a unique chlorine odor, which is often referred to as the smell of bleach. In the process of tap water treatment, in order to prevent the growth of microorganisms in the water supply system, it is necessary to maintain a certain residual chlorine content in the water supply system. Therefore, municipal tap water often has this smell, and this bleach smell is difficult to reduce to a level that people cannot perceive. . Especially in areas with high temperature and in the summer when the microorganisms grow rapidly in high temperature, it is necessary to increase the amount of chlorine, and the taste of tap water is more obvious.
  7. Iron: Iron is a metal that exists widely in nature, and it is also commonly found in water. When the water contains a lot of iron, you will feel a rusty smell, which will obviously affect the taste of beverages, and can stain laundry and water delivery. equipment. Iron has no toxic effects on human health, but only affects use. The standard limit for the evaluation of iron is organoleptic rather than toxicological. Suspended tan or red iron deposits can be offensive to the senses.
  8. Manganese: In nature, manganese exists as a compound in various salts, often coexisting with iron compounds. Manganese is an extremely important trace element for plants and animals. Manganese concentrations in the water supply exceeding 150 μg/L, like iron, stain clothing and add an unpleasant taste to beverages.
  9. Permanganate index: It is a comprehensive index to express the degree of water pollution by the consumption of potassium permanganate when oxidizing organic and inorganic reducing substances in water. The standard limit for drinking water is less than 3mg/L. The heavier the water pollution by organic matter, the higher the permanganate index. The amount of chlorine used in disinfection is also high, and the taste of the water is also worse.

The influence of the substances contained in the pollution on the taste of water:

  1. Decomposition of humus in nature and metabolic products of microorganisms in water The main substances in the decomposition of humus in nature include 1,10-dimethyl-9-decalinol , methyl isoborneol, inversion, 2-cis, 6-nona-n-alkane, methyl mercaptan, dimethyl sulfide, etc., these substances express the taste of earthy, musty, cucumber, rotten cabbage smell, rotten vegetables, etc.
  2. Some man-made pollutants Man-made pollution includes many, including phenol, dimethyl trisulfide, nitrite and organic matter. For example, phenol has a medicinal taste; dimethyl trisulfide has a garlic taste; nitrite has a salty and bitter taste.

3. High-quality drinking water

Drinking water includes “quantity” and “quality”, and the quality of drinking water is directly related to the taste of water. Due to the different geological environments in which groundwater is located, not all mineral waters mined are delicious. Water with good taste is called delicious water in foreign countries.

Delicious water generally has the following characteristics:

  1. The total hardness (calculated as calcium carbonate) is 50-150 mg/L;
  2. It contains a certain amount of oxygen and carbon dioxide;
  3. The content of minerals in the water is appropriate, especially some minerals The substance content must be balanced, otherwise the taste of the water will be bad, such as slightly sweet when the calcium content is appropriate; astringent taste when the iron content is too high; salty when the sodium content is high; bitter taste when the magnesium content is too high. The ions that Japan studies on drinking water are calcium, potassium, silicate, etc., while magnesium, sulfate, etc. are the main components of drinking water;
  4. The best temperature for drinking water is 14°C;
  5. Small molecular clusters
  6. Eliminate the odor and odor caused by foreign pollutants, such as mold, algae, rust, etc.;
  7. Eliminate the odor caused by by-products of disinfectants such as ozone in the production process .

For the taste of high-quality drinking water, the following two points should be noted:

  1. Due to the different mineral content in tap water, tap water in different regions has a certain special taste (taste) or flavor. The taste is the commonality, while the flavor is the individuality or speciality.
  2. Some tap water contains unbalanced minerals, which affects the taste of tap water, which makes many people think that tap water is not as good as pure water. In fact, since pure water does not contain any minerals, the water feels very thin to drink, not as sweet and refreshing as high-quality drinking water.

4. how to improve the taste

Generally speaking, when municipal tap water leaves the factory, the water quality can meet the requirements of national standards, but due to the pollution of the pipe network and secondary water supply, the tap water of domestic user terminals may not meet the requirements of national standards. Therefore, it is particularly necessary to install a water purifier at the terminal. At present, common water purification technologies on the market include ultrafiltration membranes, activated carbon, reverse osmosis membranes, and anion and cation exchange resins. Ultrafiltration membrane, namely hollow fiber ultrafiltration membrane, is a kind of polyacrylonitrile. A large number of micropores with a diameter of 0.01 μm are distributed on the tube wall of the hollow fiber membrane. Therefore, in addition to retaining physical pollution such as sediment, rust, solid impurities and colloids in water, ultrafiltration water purifiers can also retain microbial pollution such as algae and bacteria in water, but it cannot remove inorganic and organic substances in water. Activated carbon has a large number of pores inside, and there are many capillaries in the pores. It is precisely because of such a rich pore and capillary structure that activated carbon has strong adsorption. The main adsorption objects of activated carbon are some organic and inorganic substances (especially non-polar molecules). For example, residual chlorine (the molecule is Cl2) is a non-polar molecule, which is easily adsorbed by activated carbon. The principle of reverse osmosis technology is that under the action of higher than the osmotic pressure of the solution, these substances and water are separated according to the fact that substances larger than water molecules cannot pass through the semi-permeable membrane. The pore size of the reverse osmosis membrane is very small, so it can effectively remove dissolved salts, colloids, microorganisms, organic matter, etc. in the water, and obtain water with high purity. Since the reverse osmosis membrane filters out all the minerals, the water has very few conductive ions, and the conductivity is very low, making it unsuitable for electrolysis. The anion and cation exchange resin adopts the ion exchange method, which can remove the anions and cations in the ionic state in the water, so it can remove the inorganic salts in the water, but the obtained water is similar to pure water. This kind of water is similar to the water from reverse osmosis, the minerals are filtered out, there are few conductive ions in the water, and the conductivity is very low, so it is not suitable for electrolysis. From the above four technologies, to provide a high-quality water that can be electrolyzed and has a good taste, a better method is to use ultrafiltration membrane + activated carbon adsorption. This technical combination can filter the physical pollution in water including rust, sediment, colloid, solid impurities, etc.; the biological pollution includes algae, bacteria, red worms, sandworms, etc.; some of the filtered chemical pollution includes residual chlorine, organic matter, Inorganic substances, etc. After filtering, most of the odorous pollutants (such as residual chlorine, humus decomposition products in nature, rust, sediment, some organic substances, some inorganic substances, etc.) are retained or adsorbed by filtration, and the taste is greatly improved. However, the ultrafiltration membrane + activated carbon adsorption water purifier cannot completely solve the bad taste caused by the high hardness and total dissolved solids, especially in hard water areas and coastal areas when the salt tide is more obvious, but as long as it is qualified The municipal tap water is raw water, which is safe and harmless after filtering. In addition, the taste of water also varies from person to person and due to different living habits. For example, in some hard water areas in the north, outsiders will feel salty after drinking this water, but local people do not.

Conclusion

There are many factors that affect the taste of water, including natural factors, such as hardness, total dissolved solids, chloride, carbonate, sulfate, etc. man-made pollution, such as chlorine in disinfectants and the main substances that decompose humus in nature , phenol, dimethyl trisulfide, organic matter, etc. After PP cotton, hollow ultrafiltration membrane interception and activated carbon adsorption, the filtered purified water can be directly consumed, and the taste will be greatly improved.

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Further reading:

reverse osmosis technology in winemaking process

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