TDS Meter: What is and what does it really measure?
TDS is the English abbreviation for «Total Dissolved Solids» and what TDS readers do is measure the total concentration of dissolved solids in water.
TDS is composed of inorganic salts. The common inorganic salts present in water are minerals such as calcium, magnesium, potassium and sodium, among others.
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HOW DOES A TDS READER WORK?
The TDS reader works by conductivity and measures the conductivity of water. It is measured in PPM (Parts Per Million).
Pure water H2O or distilled water does not conduct electricity, so if a TDS reader is immersed in fully distilled water the result will be «0» or a very low number if there are traces of minerals in the water. It is the charge of electrons that make up the minerals what conducts electricity. In short, water with more minerals conducts more electricity than water without minerals.
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Case study:
If we put kitchen salt in a distilled or demineralized water we can see that the reading of the TDS meter increases depending on the amount of salt we add. Adding too little salt can change the conductivity considerably and change the value from 0 to 500 ppm just with a bit of salt.
Salt is a sodium chloride and is composed of two minerals. If we add these two minerals, sodium and chloride to water, the electronic charge of these elements conduct electricity, increasing the conductivity and measurement of TDS in the water.
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CAN I KNOW WHAT MINERALS ARE DISSOLVED IN WATER WITH A TDS READER?
No. It’s not possible to distinguish the different minerals in the water. The TDS meter calculates a general conductivity measurement that depends on the overall amount of minerals dissolved in the water. Therefore, we cannot know what levels of calcium, magnesium or potassium, for example, the water has.
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DOES THE TDS READER INDICATES THE QUALITY OF THE WATER?
No. In order to know the quality of the water it is necessary to make a complete analysis of the water.
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Case study:
If a TDS meter is immersed in a glass of weakly mineralised bottled water, the reading value will be very low, around 50 ppm.
If it’s immersed in a more mineralized bottled water it will reach a number around 500 ppm.
If it’s immersed in a high mineralization water, it will reach a number higher than 1500 ppm.
In all three cases they are bottled water suitable for consumption but with different level of minerals and conductivity. We cannot conclude that water with fewer minerals is better than water with more minerals, as reading the TDS monitor does not provide a conclusion about their quality.
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WICH WATER IS THE MOST RECOMMENDABLE?
Define which water is more advisable to consume, if with many or few minerals, is going to depend on each person and in function of their necessities.
For people who don’t suffer any illness and who live in countries where temperatures are generally high, it’s better to consume a mineralized water, since the mineral charge is the one that provides a correct hydration. An example of this are isotonic drinks for athletes with a high mineral content.
In contrast, for people who suffer from nephritic colic, they should consult their doctor and see which water is best adapted for this type of people, but surely a weak mineralization water.
As with babies from 0 to 6 months old, who have their digestive system still in the process of development and the best food they assimilate is breast milk or replacement milk, it is recommendable to prepare the baby bottles with weak mineralisation water, so we don’t add minerals at this stage when the baby is not yet able to assimilate them well.
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MALPRACTICES WITH THE TDS READERS
In Spain there is a malpractice of the TDS meters to generate doubts in the consumer mind and persuade him in the purchase of filtration systems that in practice does not need. These practices have been denounced by consumer organisations such as the OCU.
Some reverse osmosis system sellers use incorrectly this meters to convince customers of the quality of their water when in fact it is the opposite. Reverse osmosis systems generate nearly demineralized water with a reading sometimes less than 50 ppm. Believe that the lower reading means better water is incorrect, because in most cases, drink mineralized water is beneficial for the health.
An osmosed or almost distilled water is not the most advisable to have a correct hydration.
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WHY THE READING OF THE TDS METER DOESN’T CHANGE WITH THE DROPSON FILTER CAN?
As we indicate in our technical communication, the Dropson filter does not act on the mineral charge. The reason is that tap water in Spain is the safest and most controlled food, our filter is designed to remove chlorine, heavy metals and other negative substances from the water, respecting the natural mineralization, so necessary for proper hydration.
So if we make a TDS test with Dropson filtered water, the value before and after filtering will be the same or similar.
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CAN A DETAILED ANALYSIS OF THE COMPOSITION OF THE WATER BE REQUESTED FROM EACH CITY COUNCIL THAT SUPPLIES THE WATER?
Yes. In these analyses we can see that every element found in drinking water complies with the quality criteria of the World Health Organization (WHO). For this reason, it is not necessary to eliminate the minerals that we consider necessary for the health.
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CAN YOU DETECT POLLUTION WITH THE TDS READER?
No, because it’s a conductivity general reading. To detect pollution is necessary to carry out a detailed analysis of the water. For this reason we have limited the use of our filter can, only on drinking water networks that complies the WHO criteria.
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SO, WHY FILTER TAP WATER IF IT’S CONTROLLED?
Usually it’s a matter of taste. In Spain the consumer prefers bottled water to tap water, mainly because of its taste. This is due to the fact that tap water, receives a post-treatment based on chlorine which, together with the biofilms existing in the pipes, influences its unpleasant taste.
The Dropson filter can is designed to eliminate bad taste and preserve the beneficial characteristics of tap water. But it also offers a double protective barrier reducing potability criteria in drinking water, such as heavy metals, chemicals or micro particles such as microplastics etc.
Visualize the extreme tests:
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USEFUL INFORMATION ABOUT THE WATER TASTE PERCEPTION
The human palate is capable to detect an endless number of details in the taste of water, beyond the bad taste. For example, a person accustomed to consume always the same brand of weak mineralization bottled water such as Bezoya, Aquarel or another, will notice a great difference in taste if it changes to a more mineralized bottled water such as Solán de Cabras, Agua de Cazorla or another.
This is because the brain is used to receiving the same taste information every time it drinks water. In fact, there are people who don’t want to drink bottled water if it’s not their favorite brand. This perception also works in the opposite direction, people accustomed to drinking highly mineralized water and who do not tolerate the taste of weak mineralization bottled water.
It is a perception of addiction to a particular taste that may be reversible if you propose to change brands for a limited period of time.
For these same reasons, there are people who instantly like the taste of the water filtered by the Dropson can, because the mineral load is close to their brand of bottled water. Other people who consume very weak mineral water need some time to adapt.
It is not due to a criterion of quality, is more about the taste of these brands due to their particular load of minerals. In order to adapt more quickly to the taste, the temperature of the water is very important. This taste differential is less noticeable when the water is cold. Using a borosilicate glass jar such as Dropson CrystalDrink and storing filtered water in the fridge allows you to get used to our technology more quickly.
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DROPSON FILTER CAN QUALITY
The Dropson filter can has been subjected to migration tests to check that all its elements are foodstuffs.
The filtration membrane is made of 100% natural materials.
Our filter is tested and controlled by SGS, the world’s leading company in inspection, testing and certification services.
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