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Xiaomi Mi TDS Pen: Real Water Tester.

Xiaomi Mi TDS Pen: Real Water Tester.

If you are not indifferent to what you drink.

For people who care about their health, Xiaomi has developed a rather simple, but at the same time very useful device - the Xiaomi Mi TDS water tester. The compact measuring device is able to show how much the water you drink complies with generally accepted mineralization standards.

In the box

The Xiaomi Mi TDS Pen water quality tester is delivered in a regular cardboard box on which the MI logo is placed on the front, an instruction on the back, and all the technical information on the right side.

The inner packaging is quite tight and protects the device during transportation.


MI TDS looks like a thick marker or pen on both sides equipped with caps.

A battery compartment is located under the upper cap, and water quality sensors are located under the lower cap.

Also, the bottom cap is a container for sampling the test fluid (natural or purified water).

On the front side there is a liquid crystal display for displaying the results, as well as a button with TDS engraving that activates the start of the test.

The body of the device is plastic and glossy. Fingerprints hides due to its color, but is prone to micro-scratches.


Weighing in at 27.4 grams, Xiaomi Mi TDS has a fairly compact size, which is 150 x 16 x 16 mm.

Operating temperature ranges from 0 to 80 degrees Celsius.

For power use two AG13 batteries with a total capacity of 160 mAh.

The measurement scale is in the range from 0 to 9990 PPM (mg / 1L), and the error, according to the manufacturer, does not exceed 2%.

Working with Xiaomi Mi TDS Pen

To measure the mineralization of water, pour it into any container or cap of the measuring device and place the sensor of the measuring device in them.

Next, press the TDS button and wait until the numbers on the screen are fixed on the final result, which may take several seconds.

According to the table, you can calculate how much this water is suitable for everyday use:
• 0 - 50 ppm - the most purified water by distillation, microfiltration or other cleaning methods. Drinking such water is highly not recommended, as it simply will wash the available salts from the body;
• 51 - 100 ppm - high-quality water that has been cleaned with household filters or water from mountain sources;
• 101 - 300 ppm - not very “clean” water, the drinking of which is quite acceptable;
• 601 - 1000 ppm - excess minerals, which can affect the taste of water;
• more than 1000 ppm - water unsuitable for frequent consumption.

Test results

As a test, the content of minerals in water, with which it is necessary to contact most often, was measured.

• tap water - 197 ppm;
• tap water through a decanter filter - 176 ppm;
• tap water through a reverse osmosis filter with mineralization - 87 ppm;
• tap water through a reverse osmosis filter with full purification - 56 ppm;
• distilled water - 9 ppm;
• drinking water from the store - 87 ppm;
• mineral water from the store - 2530 ppm.

As you can see, mineral water has a surplus of all kinds of elements, which with prolonged use can negatively affect health (hair loss, damage to teeth, nails, etc.). Similar can be observed in people who returned from mineral spas and for 7-10 days drinking excessively this useful (up to a certain point) water.

What you need to know about the general mineralization of water?

Total Mineralization of Water (TDS) is an indicator of the amount of substances dissolved in water, both inorganic and organic.

Inorganic substances — calcium, magnesium, potassium, and sodium salts — in the form of bicarbonates, chlorides, and sulfates that exist in water as ions — make up most of this indicator.

The more ions, the greater the current strength between the electrodes lowered into the water. This is the principle of operation of the Xiaomi Mi TSD Pen.

In the USA, this value is called Total Dissolved Solids (TDS) - the total amount of dissolved solids. Therefore, the device can be called a TDS meter or salinometer.

The unit of measure for a TDS meter is the number of milligrams of salts per 1 liter of water - mg / l, or ppm (parts per million) - 1 part of the substance per million parts of water. In practical calculations, 1 mg \ l = 1 ppm.

It is important to understand for yourself the difference between total water mineralization (TDS) and “water hardness”.

“Water hardness” is a part of general mineralization, caused only by calcium and magnesium salts (without sodium, potassium and others).
Moreover, the "hardness" of water consists of two parts - temporary (disposable) and permanent (unremovable).

The removable “hardness” - leaves when boiled - turns into insoluble scale (due to hydrocarbonates), unremovable (permanent) - does not go into scale (chlorides and sulfates).

The degree of “disposable hardness” of the water you use is easy to determine: measure the TDS “before” and “after” boiling. It is advisable that the temperature of the test water be approximately the same (if your device does not adjust for temperature). The difference in measurements will be an indicator of “removable stiffness”.

The standards given in the instructions for TDS meters apply only to “drinking water”, without affecting the range of so-called “Mineral waters”, the degree of general mineralization of which is incomparably higher.

For Russia, the permissible TDS of drinking water is 500 mg / l, for the United States - 1000 ppm (mg / l). It is this water, whose TDS does not exceed 1000 mg / l, is called fresh.

You need to know this and not panic when your device, inserted into a container with an elite “mineral water”, shows the values from the “unsuitability” zone for drinking water. So it should be, and only confirms the fact that the greater the degree of mineralization of the mineral water you use, the less suitable for constant (continuous) use. Such waters are used in short courses according to special medical indications.

I would also like to warn the owners of complex treatment systems from drinking very low mineralization water (from 100 to 50 and lower mg / l) for drinking. By drinking this almost “distillate” systematically, you grossly upset the water-electrolyte balance in your body, which is fraught with serious health problems.


Thus, if you are not indifferent to what you drink, the Xiaomi Mi TDS Pen tester can be an indispensable assistant.

Original Xiaomi Mi TDS Pen Tester



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