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Made in the UK

The Doby

The Doby whole house water filter system is the ideal choice for an entire house.






Improve the taste and smell of your mains water and remove chlorine and sediments. If you are looking to reduce scale in your water you need the Doby Hardness whole house water filter.

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

The Doby is an undersink whole house water filter system 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).
  • 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, odour and sediment)
  • 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 £64.99 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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