The difference between DI and RODI filtration

It’s a fact that hard water contains a much bigger proportion of minerals compared to soft water. This can be seen when window cleaning, as if the water hasn’t been purified and is left on the glass, it can leave streaks or spots on the glass.

When cleaning windows, to prevent streaky windows, we often recommend either RODI or DI filtration. But what’s the difference between the two?

DI filtration (Deionisation)

However, deionization (DI Filtration) is the process for removing ions from a solution, e.g., salt, minerals, iron, and copper. In the deionization process, water flows through a resin bed filter where minerals particles are bound to resin beads with corresponding charges. The excess non water ions are attached to the resin beads and remain in the resin, while pure water continues flows through the filter vessel.

This process is favoured in areas of soft water, where RODI is less necessary. Soft water areas have less chemicals in their water that can damage the membrane, and so only require the resin for purification.

DI is typically a more cost-effective option than its Reverse Osmosis counterpart for this reason. If a business is operating exclusively in soft water areas may find it beneficial to opt for these sorts of cleaning systems.

However, if you prefer the freedom of being able to clean anywhere in the world – and a slightly costlier system is not a concern of yours – than RODI may be the correct option.


RODI (Reverse Osmosis) removes all containments for the water, for example, when water flows from a concentrated side of the membrane to a less concentrated side which provides the pure water. By applying more pressure, the excess water is forced through a semipermeable membrane resulting in purer water.

The process works is that not only water goes through reverse osmosis which removes up to 95% of the continents and dirt out of the water, but also goes through a DI filtration (Deionization).

When water is first applied to a RODI system, it goes through a prefiltration stage, which includes a carbon filter and a sediment filter to help remove salt and chlorine that could damage the membrane, this help when water passes through the RO membrane where other contaminants are removed. Sometimes there is still excess amount of contaminants left over which are normally run through a DI filter (Deionization) which removes all the remaining total dissolved solids from the RO membrane.