4.5 x 20 inch Carbon Block Water Filter Cartridge

This is the replacement cartridge for our Doby water filter. This cartridge will fit other 20" 'Big Blue' style water filter housings.

The Doby mains water filter is the ideal choice for a small house with up to four occupants.

Improve the taste and smell of your mains water and remove chlorine and sediments.

If you wish to treat hard water please select the hardness reduction option and your cartridge will have siliphos crystals added before sending it to you. (hardness option currently not available)

Cartridge details:

• CTO 4520-05 (chlorine, taste and odour)
• 4.5" x 20"
• 5 micron
• >26,000 gallons @ 3.0gpm or 12 months; whichever comes first
• Certified NSF/ANSI standard 42 NSF
• Certified by ISO 9001
• Performance tested and verified by independent laboratory testing
• We send out an email every 6 months to remind you to check your filter performance.

Why do I need to change the o-ring?

You can tell if the seals start leaking, which is obvious, I know.

Even if there are no leaks you may find that the profile of the O ring becomes flattened because of prolonged time under compression. The cross section should be round and if it's not it may not seal easily.

However, I recommend that you replace the O rings every two or three years as a precautionary measure.

One of the main reasons for changing O rings periodically is that as they age and compress, the housing bowl needs to be tightened excessively. That leads to difficulty loosening the bowl from the cap next time the cartridge needs to be replaced.