Stages in Reverse Osmosis Water Filter Systems

Want to know more about the stages in the reverse osmosis water filter system?

1st Stage: Sediment Pre-Filter

The Sediment pre-filter removes dirt, rust and sediment particles down to 5 microns. There are several different types of sediment cartridges.

Sediment Pre-Filters protect the 2nd Stage Filter. Carbon Filters block easily without a sediment pre-filter. 

2nd Stage: Carbon Pre-Filter

The Carbon pre-filter captures chlorine, taste, odours, pesticides and herbicides. There are several different types of carbon filters.

Carbon Pre-Filters protect the 3rd Stage Filter. Membranes deteriorate easily in the presence of chlorine.

3rd Stage: Reverse Osmosis Membrane

Reverse osmosis membranes reject 95% of pollutants found in the water. They reject (remove) 95% of Total Dissolved Solids (TDS) down to .0001 Microns. There are several different types of reverse osmosis membranes.

Reverse osmosis membranes filter viruses, bacteria and parasites. Repel heavy metals and remove Fluoride and Hydrocarbons, as well as other contaminants. 

4th Stage: Reverse Osmosis Tank

Reverse osmosis tanks collect the water coming from the membrane. RO tanks fill up at a flow rate of 16 L/H approximately. There are several different sizes of reverse osmosis tanks. Standard being 8 litres.

5th Stage: Carbon Post-Filter

The carbon post-filter filters the water coming from the reverse osmosis tank. They remove any taste left in the water after the water is collected in the tank. It is also called polishing filter.

The carbon post-filter captures any taste left behind just before you open the tap.

6th Stage: Alkalising Filter (optional)

The pH of the water after the reverse osmosis membrane is acidic. Therefore, an alkalising filter is often installed as the final stage to raise the pH of the water to 9. There are several different types of alkalising filters.

Alkalising filters raise the pH of the water and can also add minerals to the water such as calcium, magnesium and potassium.