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TDS Meters

TDS meters measure total dissolved solids for quick checks of source water, filtration systems, and lab samples.

Pick portable and pen style models from HM Digital and Apera Instruments when you need a water TDS meter for spot testing.

For continuous readouts at tanks or RO systems, choose a TDS monitor with clear displays and simple calibration.

When portability matters, a handheld TDS meter keeps results consistent with probes and solutions from Ohaus and Azzota.

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Frequently Asked Questions

What is a TDS meter and what does it measure?

A TDS meter (total dissolved solids meter) reads water’s conductivity (µS/cm) and, using a conversion factor (typically 0.5–0.7), estimates dissolved minerals in ppm or mg/L. It shows total load, not which ions are present.

What is a good TDS level for drinking water?

With a water TDS meter, ≲300 ppm usually tastes clean; 300–500 ppm is often acceptable; above ~500 ppm many users notice scale or off-flavor. Suitability also depends on the actual ions. For complete water analysis, combine with pH meters and water quality meters.

How do you calibrate a TDS meter properly?

Rinse with DI water, blot dry, immerse the TDS tester in a fresh 342-ppm NaCl standard at room temperature, wait for a stable value, then adjust the reading to the standard. Recheck after major temperature changes. Use certified calibration weights and standards for accurate results.

How should a TDS meter be cleaned and stored?

After testing, rinse the probe with DI water, shake off, cap it, and store tds meters cool and dry, away from sunlight. Don’t leave the sensor soaking in solutions. Calibrate on a regular schedule.