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Made in the UK

Doby TMF Filter

Taste, heavy metals and fluoride mains water filter. With full fitting instructions and free UK standard delivery.



Product SKU: PRAA342



Fluoride, Metals and taste, odour, chemicals and sediment (TOCS) filtration with this double Doby mains water filter system.

Stage one removes fluoride then stage two filters metals and improves taste and odour while also removing chemicals from your cold water tap supply.

Your kit will include:

  • 2 x 20 inch big blue filter housings
  • 1 x white double housing bracket
  • 1 x 4.5 x 20" GAC/KDF cartridge for removal of heavy metals and chemicals and to improve taste and odour of your mains water.  
  • 1 x 4.5 x 20" Activated Alumina cartridge for fluoride reduction
  • Either 1/2 for 15mm or 3/4 for 22mm ports
  • 2 x Isolating flexis (no need for extra ball valves)
  • 1 x double check valve - either 15mm or 22mm
  • 1 x housing spanner
  • Fitting instructions for your plumber

Cartridge details:

  • 1 x 4.5'' x 20" activated alumina fluoride removal filter cartridge
  • 10 micron
  • Temperature range 40°F (4°C) to 100°F (38°C)
  • Pressure range 25 psi (1.7 bar) to 100 psi (6.9 bar)
  • Capacity 10,000 mg/l
  • Flow rate - 15 lpm / 3 gpm
  • Reduction ability - 10ppm to <0.2ppm (93% reduction)


  • 1 x 4.5 x 20" canister containing GAC/KDF filter medium (GAC10N/KDF-BOM)
  • 5 micron
  • 24,000 gallons @ 2.0gpm or 12 months; whichever comes first
  • Certified NSF/ANSI standard 42 NSF
  • Certified by ISO 9001
  • Performance tested and verified by independent laboratory testing

What order do the cartridges go in?

In most circumstances the lowest micron rated cartridge goes last in the sequence (on the water out side). For the Doby Taste, Metals and Fluoride mains water filter the 5 micron GAC/KDF cartridge goes first in the sequence, followed by the 10 micron activated alumina cartridge.

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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