Shake: Always make sure to shake excess water off the meter before dipping it into a water sample, even when measuring the same water source.
Stir/tap: After dipping the meter in the water, always lightly tap it against the side and stir the meter to remove any lingering air bubbles or electrical charges.
Positioning: When taking the reading, always make sure to hold the meter straight up without it touching the sides or bottom of the glass/beaker/cup. The probes should be suspended as close to the center of the water sample as possible.
Time: The longer the meter is in the water, the more accurate the reading will be. For best results, allow at least 10–20 seconds of dwell time before recording the value.
Temperature: 25 °C (77 °F) is the ideal temperature for accurate conductivity and TDS readings, even if your meter features Automatic Temperature Compensation (ATC). Measurements taken at significantly different temperatures may yield less reliable results.
Rinse: When switching between very low and very high ppm water, rinse the probes with distilled water to prevent residue or mineral build-up that could skew readings.
How do you get an accurate reading from a TDS or conductivity meter?
To get an accurate TDS or conductivity meter reading, follow these six steps: (1) shake off excess water, (2) stir to remove air bubbles, (3) hold the meter centered in the sample, (4) allow sufficient dwell time (10–20 seconds), (5) measure at 25 °C (77 °F), and (6) rinse the probes when switching between very low and very high ppm water.
When measuring pure water TDS on a purifier, always wait at least 30 seconds after the water starts flowing before collecting your sample. This prevents TDS creep — a temporary spike in TDS readings caused by dissolved solids that accumulate in stagnant water inside the purifier.