The water goes through the pre-filters first, where sediment and organic chemicals are filtered out of the water.
This makes the water cleaner and safer to drink and protects the sensitive RO membrane from damage and clogging.
The pre-filters, and specifically the two carbon pre-filters, play an especially important role in removing chlorine from the water.
Chlorine can damage the RO membrane, reducing its ability to reject impurities. This allows more contaminants to pass through the membrane, which compromises water quality.
That’s why it’s also important to replace the pre-filters on time before they degrade to a point where they allow some chlorine through.
The first pre-filter is a standard sediment filter.
It removes large particles suspended in water such as silt, dust, rust, and sand. This reduces water turbidity and ensures the sediment doesn’t clog the carbon filters.
The next two pre-filters are both carbon filters, though different types of carbon.
The first is a GAC or granular activated carbon filter. It consists of loose granules of activated carbon that adsorb chemicals like chlorine and pesticides from the water.
The second is a carbon block filter. It’s still made from activated carbon, but the carbon particulates are compacted into a block.
Because of its design, the carbon block filter has a bigger surface area for water to interact with.
This improves its ability to adsorb chemicals like chloramines, herbicides, and other organic substances from the water.
Combined, the two carbon filters remove almost all chemicals that affect the taste and smell of the water. They also remove harmful chemicals.