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Total Dissolved Solids

What is TDS (Total Dissolved Solids)?

TDS stands for Total Dissolved Solids. The total mass of all dissolved minerals and salts in a water sample, in mg/L or ppm. The single most important number for sizing an RO system.

  • BWRO

    RO designed for feed waters with TDS roughly 500–10,000 ppm — typical of tap water, wells, and many industrial streams.

  • SWRO

    RO designed for seawater feed (~35,000 ppm TDS), running at high pressure (~800 psi) with very high salt rejection (>99.7%).

  • GPD

    The daily permeate flow rate of an RO element under standard test conditions. The number after the dash in residential model names (e.g. RE-1812-75 produces 75 GPD).

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