neutralising filters

Choose from a wide range of neutralizing filters for the conditioning of water produced by desalination installations. Use these filters for improved taste and prevention of corrosion in your freshwater system.

Low pH

Water with a low pH value, such as product water from desalination plants (both evaporators and reverse osmosis type water makers), is often corrosive and tasteless. This so-called ‘acid condition’ is due to the presence of free carbonic acid gas (CO2) and a lack of natural minerals.

Neutralising / mineralising

To make this water neutral or slightly alkaline, it should be neutralized or mineralized. To ensure complete removal of CO2, the water can be filtered through a bed of neutralizing filter media, named “EWT compound.” In the low-pressure filtration process, the CO2 reacts with the EWT compound to form natural bicarbonates and calcium (Ca2+). Both ions will contribute to less corrosive water.

EWT compound

In the past, it has been common practice to use marble neutralizing (mineralizing), though the reaction is slow and equilibrium is difficult to reach and maintain. EWT compound is now preferred due to its quick and complete action. Its special structure makes it rapidly and uniformly soluble.

EWT compound is a granular medium, packed in 25 kg bags. The average consumption of material is 1 kg (2 lb) on 70 m3 of water. It is sufficient to partially refill a few times per year to replace the material that has been dissolved in the water in due process. Upon refilling, the filter must be flushed by reversing the water flow to remove dust and contamination from the fresh filling material. We would furthermore advise you to occasionally flush the filter to loosen the filter bed.


The HDN GRP filters are made of 100% composite fiberglass corrosion-resistant material with a polyethylene inner shell and are corrosion-resistant.


The HDN GRP filters are supplied with PVC-U piping and manual (three-way) ball valves for full operation, including backwash of the neutralizing filter. The piping diameter is dependent on the filter model.

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