TDS & EC Meter 2.0
Resources and FAQs
TDS stands for Total Dissolved Solids. It is the measurement of all the dissolved substances in a water sample. These “dissolved solids” are mostly inorganic salts like sodium, calcium, magnesium, and potassium cations along with chloride, bicarbonate, carbonate, phosphate, sulfate, and nitrate anions.
Truly accurate TDS measurements must be performed in an analytical laboratory. The water sample is weighed and then heated under tightly controlled conditions to evaporate the water. The remaining weight of the leftover “solids” is used to calculate the TDS in the water sample. However, this level of accuracy is not necessary for most at-home testing applications. It is expensive and must be performed in a qualified laboratory. Using a TDS meter is a much faster and affordable method.
Why is the TDS important?
Let's make this clear - TDS is not a measurement of harmful substances or pollutants. TDS is simply a measurement of all substances dissolved in water. Distilled water has a TDS of 0.0 ppm, while the ocean has a TDS of 10,000 ppm. Both water sources are "safe". An acceptable TDS is relative to the water being tested and what the water is used for.
Here is an example: If you tested the TDS of distilled water and found it to be 300 ppm, you would know that the water was not distilled. Perhaps the water purification system was faulty, or something had contaminated the distilled water. So, TDS testing is like a watchdog. It will tell you if things are not as they should be.
How do TDS meters work?
TDS meters do not directly measure the total dissolved solids. Remember, the TDS is determined by evaporating the water and weighing the remaining solids. Instead Hand-held TDS meters measure electrical conductivity (EC). Dissolved inorganic substances like salts and minerals conduct electricity. The higher the concentration of these substances in the water sample, the higher the electrical conductivity. A TDS meter performs a few calculations based on the EC value to arrive at an estimated TDS reading. This is what you see on the screen.
The great thing about this meter is that it works for almost any type of water testing you have in mind:
Nutrient levels in a hydroponic setup
TDS in swimming pools, spas and hot tubs
Aquariums and fish tanks
And many more
However, there are also some applications where a TDS meter is not a suitable device for testing. These include general drinking water filtration systems, water hardness, and saltwater aquariums for example. Find out more in the FREE User Guide below.
When to calibrate your meter?
Your TDS meter is factory calibrated (at 342 PPM), so you can use it straight out of the box. However, if you wish to re-calibrate it, check the instructions in your product manual. Here's when you might want to consider calibrating your TDS meter:
After prolonged usage, recalibration may help to increase the meter’s accuracy.
TDS meters are more accurate when calibrated at levels that are close to the sample being tested. So, if you’re measuring samples that are around 1000 ppm, for example, it’s recommended that you calibrate the meter for that specific value.
Helpful Resources and Downloads
If you want to learn more about your drinking water or how to take care of it, the U.S. EPA website is a great resource to look up.
Frequently Asked Questions
Got a question that is not listed? Email us at [email protected]