Generally, the TDS (Total Dissolved Solids) of water produced by RO (Reverse Osmosis) purification equipment must be ≤50 to be considered potable water, safe for drinking directly. However, even after installing an RO system, if the TDS value remains high, the quality of the RO purification equipment may be questioned. Typically, higher electrical conductivity indicates higher salt content and consequently higher TDS. A higher TDS value signifies that the water contains more impurities. If the TDS is elevated, it indicates increased impurities in the water, leading to reduced water purity that fails to meet the requirements of the planned project.
TDS Measurement Method:
End customers and dealers often habitually measure TDS directly from the tap. This method can lead to inaccurate readings. The standard measurement procedure is:
- Disconnect both the pressure tank and the post-filter.
- Allow the system to operate normally under standard water production mode for approximately 9-11 minutes (for newly installed machines, the flushing time should be extended to about one hour).
- Collect a water sample from the purified water outlet of the RO membrane housing for testing.
The TDS meter has become one of our commonly used tools for water quality testing. To use it:
- Open the probe cap of the TDS meter.
- Press the power button; once the screen activates, immerse the probe into the water sample to be tested.
- Wait for the reading to stabilize, then press the ‘HOLD’ button.
- Remove the TDS meter and read the displayed value.
- After testing, wipe the TDS meter clean.
The TDS value measured from a pure water RO system reflects the amount of dissolved substances present in the water. A lower value indicates fewer dissolved solids. TDS is measured in milligrams per liter (mg/L), representing the number of milligrams of dissolved solids contained in one liter of water. These dissolved solids include:
- Dissolved salts (calcium ions, magnesium ions, etc.)
- Ionic organic compounds (ammonium acetate, sodium sulfate, etc.)
- Some heavy metal ions (chromium, zinc, lead, copper, etc.).
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