Compatibility | What it reduces | Specs | How often to change | How to replace | FAQs | Reviews

Compatibility

This 4.5" × 20" activated carbon block replacement cartridge is designed for our Doby whole house water filter, and is compatible with most standard 20" Big Blue® style filter housings that accept 4.5" × 20" cartridges.

Installed as part of a whole house water filtration system, it helps reduce chlorine, improve the taste and odour of mains water, and filter fine sediment before the water reaches every cold water tap in your home.

Not sure if this is the right replacement cartridge for your filter housing? Contact us and we'll be happy to help you identify the correct cartridge before you order.

What it reduces and what it doesn't

This 4.5" × 20" activated carbon block replacement cartridge is designed for whole house mains water filtration. Made from coconut shell activated carbon, it helps reduce chlorine, improve the taste and odour of drinking water, and filter fine sediment before the water reaches every cold water tap in your home.

If you need to help reduce limescale, the cartridge can be used with the optional hard water insert (Siliphos crystals). For fluoride, heavy metals or bacteria, you'll need a filtration system specifically designed for those applications.

Specifications

The following specifications will help you confirm compatibility and understand the filtration performance of this 4.5" × 20" activated carbon block replacement cartridge.

How often to change and signs it needs changing

Replace the cartridge every 12 months, or after filtering approximately 98,420 litres (26,000 US gallons), whichever comes first. Regular replacement helps maintain effective chlorine, taste, odour and sediment reduction.

Typical signs that it's time to replace the cartridge include:

• Reduced water flow.
• The taste or smell of chlorine beginning to return.
• The cartridge reaching its recommended service life.

To help keep your filter performing at its best, we'll send you a reminder email every six months so you know when it's time to check your cartridge.

How to replace

Replacing the cartridge is straightforward and only takes a few minutes.

1. Turn off the water supply and open a downstream cold tap to relieve the pressure.
2. Using the housing spanner, unscrew the filter housing bowl. As a 20" housing will contain water, have a container or towels ready to catch any spills.
3. Remove the old cartridge, rinse the housing bowl and inspect the O-ring. Clean, reseat or replace the O-ring if necessary.
4. Fit the new cartridge and screw the housing bowl back onto the cap by hand. Do not overtighten.
5. Turn the water supply back on, check for leaks, then flush the new cartridge for 1–2 minutes to remove any harmless carbon fines before use.

FAQs

Will this cartridge fit my water filter?

This cartridge is designed for our Doby whole house water filter and is compatible with most standard 4.5" × 20" Big Blue® style filter housings. If you're unsure whether it's the correct replacement for your system, contact us and we'll be happy to help before you order.

What does this carbon block cartridge reduce?

The activated carbon block helps reduce chlorine, taste, odour and fine sediment from treated mains water. It's designed to improve the quality and taste of water throughout your home while leaving naturally occurring minerals such as calcium and magnesium in the water.

Can I use this cartridge to help reduce limescale?

Yes. If you select the optional Siliphos hard water insert, the cartridge will help reduce limescale forming in pipework and appliances. It does not soften the water or remove dissolved hardness minerals.

How often should I replace the cartridge?

Replace the cartridge every 12 months, or after filtering approximately 98,420 litres (26,000 US gallons), whichever comes first. If you notice reduced water flow or the taste or smell of chlorine returning sooner, it's time to fit a new cartridge.

Do I need to replace the housing O-ring?

We recommend inspecting the housing O-ring every time you change the cartridge. Over time, O-rings naturally compress and lose their original shape, making it more difficult to achieve a reliable seal. As a guide, replacing the O-ring every two to three years helps maintain a watertight seal and makes future cartridge changes easier.

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