Demineralized Water also known as Deionized Water; Water that has had its mineral ions removed. Mineral ions such as cations of sodium, calcium, iron, copper, etc and anions such as chloride, sulphate, nitrate, etc are common ions present in Water. A DM Water System produces mineral free Water by operating on the principles of ion exchange, Degasification, and polishing.

Raw Water is passed via two small polystyrene beads filled (ion exchange resins) beds. While the cations get exchanged with hydrogen ions in first bed, the anions are exchanged with hydroxyl ions, in the second one.

Ion-exchange is a rapid and reversible process in which impurity ions present in the Water are replaced by ions released by an ion-exchange resin. The impurity ions are taken up by the resin, which must be periodically regenerated to restore it to the original ionic form.

When resins are exhausted - the cations Resins are regenerated with Hydrochloric acid (Hcl) and the Anion resins are regenerated by caustic Soda (NaOH) solution. So the same resins can be used over and over again to produce the DM water.

Typically, DM plants produce TDS < 30 ppm at outlet, depending upon the raw water TDS. For TDS < 5 ppm- One needs to consider Mixed Bed (MB) unit after DM plant.

Water enters the unit through the inlet distributor at the top of the vessel, and is evenly distributed across the resin bed. As the water flows through the resin bed, its ionic contaminants are exchanged for H and OH ions on the resin beads. This removes the ionic contaminants from the water, producing highly purified Demineralized water. The treated water then passes through the false bottom under drain strainers to the outlet piping at the bottom of the Unit. When the unit’s capacity is exhausted, regeneration begins. The resin is backwashed and hydraulically classified based on their densities, and after the bed settles, regeneration is carried out. Caustic Sodium hydroxide is introduced through the down flow.

Regenerate distributor, and acid is introduced through the up-flow regenerate header. The interface collector receives spent acid and caustic for disposal. A slow rinse displaces regenerate acid and caustic, then the full bed is rinsed with service water. The vessel is drained until the water level is just above the bed surface. The resins are then re-mixed with air. The vessel is refilled and the bed is rinsed before the unit is returned to service.


  • FRP, MSEP, MSRL Vessels as per requirement.
  • Manual, Semi-Automatic and Automatic features are provided.
  • Pneumatic and electrical operating automatic valves can be provided.
  • Automatic control and electrical cabinet.
  • AGUAPURO offers De-Mineralization Plants, are available in Two Types, Mainly Two Bed DM Plants and Mixed Bed DM Plants. However, DM Plants are also available with Weak Base & Strong Base Cation & Anion Exchanger.
  • DM Plants are also available with Degasification System to remove alkalinity physically without using chemicals (Saves NaOH)

The Systems have Following Configuration based on the water report or parameters:

  • SAC – SBA
  • SAC – WBA – SBA
  • WAC – SAC – WBA – SBA – MB1 – MB2
  • WAC – SAC – DG – WBA – SBA – MB1 – MB2

AGUAPURO series DM Plants (Two Bed ) are available in various sizes having cation and anion exchanger unit with 200 mm to 2000 mm diameter with either Valves or Multi Port Valve depending upon the sizes and customer requirement.

In Two Bed DM Plant, Strong Acid Cation Exchanger and Strong Base Anion Exchanger resin are used for reducing Total Dissolved Solids up to 2 - 5 ppm. To check the treated water quality at the outlet, conductivity meter is provided. Degasification unit is also provided to decrease the load on Anion Unit.

Cation Polisher Unit is also available to achieve Acidic Water Quality for Specific Applications.

DM Plant produces Treated water having Conductivity less than 10 mS/cm (for Two Bed) and less than 1 mS/cm with pH as desired.