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Made in the UK

Moby Hard Water Filter

Our Moby hard water filter is a cost effective alternative to a water softener.






The Moby Hard Water Filter is perfect for medium hard water areas. However, if you live in a high or very hard water area, such as the south east of England, then the most effective hard water filter for you is our Moby OneFlow, Moby Taste and OneFlow, or even our whole house Doby OneFlow Hard Water Filter.

Our Moby hard water filter is a cost effective alternative to a water softener. The siliphos crystal inserts that we add to the carbon block cartridge change the chemical properties of the dissolved carbonates so that the scale doesn't become a residue and stick to your household appliances.

This filter plumbs into your mains water and also filters out chlorine, chloramines and other chemicals and organic compounds. There is no need for a separate water filter tap.

When fitting a Moby mains water filter please allow for a minimum of H 38cm x W 30cm x D 18cm.

Your kit will include:

  • 1 x big blue filter housing
  • 1 x white housing bracket
  • 1 x 5 micron activated carbon block cartridge (Watts WCBFF975) with siliphos crystal inserts to reduce hardness.
  • Either 1/2 for 15mm or 3/4 for 22mm ports
  • Isolating flexis (no need for extra ball valves)
  • 1 x double check valve
  • 1 x housing spanner
  • Fitting instructions for your plumber

Cartridge details:

  • Watts WCBFF975 coconut shell carbon block filter cartridge for chlorine, taste, odour and sediment reduction with siliphos crystal inserts to reduce hardness.
  • 5 micron / 4.5 x 10"
  • Outperforms GAC cartridges as it has superior chlorine reduction (up to 99%), lower pressure drop, will not channel and costs less than a GAC cartridge.
  • Media wrap between centre tube and carbon block to reduce carbon fines.
  • 100% coconut shell carbon.
  • FDA grade components and materials.
  • Recommended flow rate - 4 gpm
  • Maximum operating pressure: 125 PSIG
  • Operating temperature: 10°C - 52°C / 50°F - 125°F
  • Chlorine reduction - >10,000 Gal @ 2 gpm
  • Tested and certified under NSF / ANSI standard 42 for materials only.

or on some occasions a Pure CTO 4510-05 cartridge may be sent. This does the same job as the Watts WCBFF975. They're just different brands.

  • Pure CTO 4510-05 with siliphos crystal inserts to reduce hardness.
  • 4.5 x 10
  • 5 micron
  • 12,000 gallons @ 2.0gpm or 12 months; whichever comes first
  • Certified NSF/ANSI standard 42 for materials only
  • Certified by ISO 9001
  • Performance tested and verified by independent laboratory testing

Replacement cartridges are £53.99 for the Moby hard water filter. We email a reminder for you to check your filter performance every six months.

Do you have to install a mains water filter under the sink?

No, you don't. You can install your mains water filter wherever the cold water supply enters your house. This could be a utility room, garage, or other location. 


* Watts components are sometimes replaced with other similar quality items due to supply chain issues. Brassware and other plumbing accessories are sourced from UK suppliers.

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