TDS & PPM


TDS (Total Dissolved Solids): Total Dissolved Solids

  • Definition: Refers to the total amount of all inorganic salts and organic substances dissolved in water. These substances come from the rocks, soil, pipes, and pollutants introduced by human activities that the water flows through.
  • Main Components: Includes minerals such as calcium, magnesium, sodium, potassium (usually harmless, even beneficial), as well as heavy metals (lead, arsenic, cadmium), nitrates, fluorides, pesticide residues, etc. (harmful).

PPM (Parts Per Million): Parts Per Million Concentration

  • Definition: It is a unit of concentration, meaning “one part per million.” 1 ppm means that for every million parts of solution, one part is solute.
  • Analogy: Just like “kilograms” is a unit of weight, “PPM” is the unit for TDS value.
  • Equivalence: 1 ppm ≈ 1 mg/L (milligrams per liter).

Conclusion: The “TDS value” we commonly refer to uses the unit PPM. When someone says “the TDS of this water is 50,” they are referring to “the total dissolved solids concentration of this water being 50 ppm.” The “IN ppm” and “OUT ppm” displayed on your product's screen refer to the TDS concentration of the incoming (source) and outgoing (purified) water.

What Do These Parameters Mean for Water Purifiers?

For water purifiers, especially reverse osmosis (RO) purifiers, the TDS value is an extremely important performance indicator.

Core Function Verification: The core function of the RO membrane is to remove most of the dissolved solids in the water. A significant change in the TDS values of the incoming and outgoing water is the most direct proof that the RO membrane is working effectively.

  • Example for Your Product: The manual mentions it can process water with a TDS of <1500 ppm, producing water with a TDS of <18 ppm. This means the desalination rate is (1500-18)/1500 = 98.8%, which perfectly proves the superior performance of its RO membrane.

Filter Life Monitoring:

  • "Barometer" for RO Membrane Performance Degradation: Over time, the RO membrane will gradually be clogged, worn down, or chemically degraded, reducing its desalination capability. Users will notice the TDS value of the purified water (OUT ppm) gradually increasing.
  • Basis for Smart Reminders: The “Filter ⚠️” replacement reminder on your product's screen is based on the change in desalination rate. The TDS sensor provides the key data for this feature.

Incoming Water Quality Assessment:

  • The “IN ppm” value allows users to have a preliminary, quantified understanding of their source water quality. If the TDS value is too high (e.g., >500 ppm), it could indicate high water hardness (more scale) or heavy pollution, highlighting the need to install a water purifier.

What Valuable Information Can Users Obtain from These Values?

Water purifiers equipped with real-time TDS display functions give users unprecedented insight and control.

Information Users Can Obtain
Value and Action Guide
Water Quality "Check-up Report"
Users can quantify the purity of their tap water (IN ppm) and purified water (OUT ppm), rather than guessing based on feel.
Real-time Monitoring of Purifier Status
By glancing at the “OUT ppm” value when dispensing water, users can immediately confirm whether the machine is working properly today, giving them peace of mind.
Scientific Judgment on RO Membrane Replacement
If the “OUT ppm” value increases significantly and consistently (e.g., from the usual 10 to 30), even if the machine hasn't yet triggered an alarm, experienced users can judge that the RO membrane may be starting to degrade and it may be time to replace the filter. This acts as a double guarantee to prevent drinking substandard purified water.
Judging Whether the Filter is Installed Correctly or the Machine is Faulty
If the “OUT ppm” value remains high after a new filter is installed, it may indicate improper filter installation (a "short circuit") or damage to the RO membrane, requiring maintenance.
Understanding Changes in Water Source
If the “IN ppm” value suddenly spikes on a particular day, it may suggest fluctuations in the municipal water supply, prompting the user to be more cautious.

Important Considerations (Must Inform Users):

  • TDS Value ≠ Water Safety: TDS pens/sensors cannot detect specific pollutants (e.g., bacteria, viruses, lead, pesticides). They only measure the total amount of conductive ions. An RO purifier that reduces the TDS value usually removes most harmful ions, but overall safety should still be ensured through authoritative certifications like NSF. It is not accurate to simply say “water with TDS = 0 is the best.” Mineral water with higher TDS may still be beneficial to health.
  • Best Indicator for RO Purifiers: For RO water purifiers, the “low and stable OUT ppm value” and “high desalination rate” are the core performance indicators.

 

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