TDS stands for Total Dissolved Solids. That’s a fancy way of saying “everything that isn’t H2O.” Think minerals, salts, metals, and even tiny bits of rock.
Your water is a soup. A very, very watery soup. TDS meters measure the “broth” part—the stuff you can’t see.
Pure water is a terrible conductor of electricity. But, throw in some dissolved minerals, and boom—it becomes a little lightning rod.
The Secret Sauce: Electrical Conductivity
A TDS meter doesn’t actually count particles. It can’t see them. Instead, it plays a trick using electricity.
Inside the meter are two metal probes. They send a tiny electrical current through your water. It’s like giving your water a gentle, invisible shock.
More dissolved stuff = more electricity flows. Less stuff = less flow. It’s that simple. The meter measures the current and shouts out a number.
That number is your TDS reading, usually in parts per million (ppm). It’s the water’s electrical handshake.
