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Doby Whole House Hard Water Filter

Are you sick of hard water? With our Doby whole house hard water filter you can effectively filter out limescale in your water. Call us on 01352838281.



Product SKU: FFK-DH



The Doby 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 OneFlowMoby Taste and OneFlow, or even our whole house Doby OneFlow Hard Water Filter.

Our Doby Hardness whole house water filter reduces scale in medium hard water areas therefore perfect for south east of England households and businesses.

An effective limescale filter, the Doby also improves the taste and smell of your mains water and removes chlorine and sediments.

The Doby hard water filter fits to your cold water tap so there's no need for a separate water filter tap.

The Doby is an undersink water filter and when fitting allow for a minimum of 28" (72cm) height x 12" (30cm) width x 7" (18cm) depth.

Your kit will include:

  • 1 x big blue 20 filter housing
  • 1 x white housing bracket
  • 1 x 5 micron activated carbon block cartridge (CTO 4520-05) with 32 x siliphos spheres inserted for hardness reduction.
  • 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:

  • CTO 4520-05 comes as standard (chlorine, taste and odour) with 32 siliphos spheres for hardness reduction included.
  • 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
  • Replacement cartridges are £76.99 and we send email reminders

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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