Conductivity is the ability of water to conduct electric current, measured in microsiemens per centimeter (µS/cm). It is proportional to ionic content and is the standard field proxy for TDS and salt rejection on RO systems. A two- or four-electrode conductivity cell applies an AC voltage and measures the current. Modern inline conductivity sensors compensate for temperature to a reference (typically 25 °C). Conductivity probes on feed, permeate, and concentrate streams are the primary continuous quality indicator for an RO plant — far cheaper and faster than gravimetric TDS. Multiply by 0.55–0.70 depending on water composition. For seawater use ~0.64; for soft brackish water ~0.50. Typical SWRO permeate is 200–600 µS/cm; BWRO permeate often 50–200 µS/cm. Higher values signal membrane issues. Ion mobility rises ~2% per °C. Sensors auto-compensate to 25 °C so logged values are comparable across seasons. ForeverPure has supplied desalination, high-pressure pumps, and energy-recovery devices to commercial and industrial customers since 2003. Contact our engineers for sizing, quotes, or technical support.Conductivity
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