# Total Dissolved Solids

Written by Jerry Ratzlaff on . Posted in Fluid Dynamics

Total dissolved solids ( $$TDS$$ ) is the matter that remains in water which remains in solution.  Within the reverse osmosis industry TDS is known as as the total cations and anions in the water.  In the ion exchange industry, TDS is the sum of either anions or cations in the water.  Units for TDS are mg/l or ppm.