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# How TDS Meter Works?

TDS meters are usually hand-held devices that can measure the Total Dissolved Solids (TDS) present in water. Although a TDS meter is usually utilized for measuring TDS of water, it can also indicate TDS of various other liquids. Use of TDS meters has become quite widespread, as there are significant concerns about the quality of water people get from their taps, water purifier, bottled water, well, bore well, river, etc. Although TDS meters do not measure quality of water, they can still be helpful to some extent. For better understanding, let’s take a look at how a TDS meter works.

How TDS meter works

The primary source of all water on the planet is rain. If we measure TDS of rain water, we can see that it is quite like distilled water that has TDS close to Zero. But when rain falls on earth and flows on land or seeps underground, it gathers various chemicals and minerals such as potassium, sodium, calcium, magnesium, etc. It also gathers various contaminants such as soil, pesticides, bacteria, viruses, algae, etc. The sum total of these chemicals, minerals, and contaminants present in the water is referred to as total suspended solids (TSS). To measure TSS, one can boil water till all of it evaporates. Any residue that is left can be weighed to measure TSS.

A TDS meter works differently, as it measures only ionized particles present in the water. These are usually calcium, sodium, magnesium, and potassium. It works by measuring electrical conductivity, which increases with an increase of ionized solids. For example, if you put a table spoon of salt in water, its electrical conductivity will increase. TDS reading will also increase as a result.

TDS measured by a TDS meter represents the equation “TDS = keEC”, where EC is the electrical conductivity and ke is the correlation factor in the range of 0.55 to 0.8. This equation provides the output in “mg per liter”, which is then converted to ppm (parts per million) by the TDS meter. Commonly used TDS meters have an accuracy of around +-10 percent.

Benefits of using TDS meter

A TDS meter can indicate whether the water you are drinking has adequate levels of minerals such as calcium, magnesium, potassium, etc. Research studies have shown that mineralized water is healthier, as compared to low TDS water. It supplies the body with essential minerals and also has alkaline properties. Water with TDS range of around 100 to 200 ppm is considered as the most ideal, as per existing research.

Limitations of TDS meter

As TDS meters do not measure contaminants such as heavy metals, pesticides, bacteria, and viruses, they cannot indicate towards quality of water. A sample of low TDS water can still harbor various forms of contaminants. That’s why water purifiers have multi-step purification process. Some of the advanced water purifiers are also equipped with re-mineralization cartridges that replenish the minerals lost during purification.

Overall, it’s clear that TDS meters can effectively measure the mineral content of water. However, they have limited use, as they cannot detect contaminants such as virus and bacteria. You can use TDS meters, but don’t assume that low TDS water is completely safe to drink.