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Moby Taste and OneFlow Hard Water Filter

Using Watts OneFlow. The best anti-scale system on the market. Perfect for hard to very hard water areas.



Product SKU: MTHA8210



Improve the taste and smell of your mains water and remove chlorine and sediments.

Also solve your scale problems with our OneFlow cartridge.

Our Moby Taste and OneFlow hard water filter fits to your cold water tap so there's no need for a separate water filter tap.

If your water is harder than 25 grains (427 ppm CaCO3) then OneFlow may not be suitable for you. Check with your local water supplier who will be able to tell you what the hardness measurement is. 

Please note that a TDS meter may give you a higher reading but it's measuring all total dissolved solids and not just CaCO3. This is another reason to contact your local water supplier.

This is an undersink water filter and when fitting allow for a minimum of H 38cm x W 60cm x D 18cm.

This is not a water softener. The Moby Taste and OneFlow Hard Water Filter is much more environmentally friendly than one of those. Take a look at our recent blog post about OneFlow by CLICKING HERE.

For more technical information have a look at the Watts website.

Your kit will include:

  • 2 x big blue filter housings
  • 1 x white double housing bracket
  • 1 x 5 micron activated carbon block cartridge (Watts WCBFF975).
  • 1 x Watts OneFlow cartridge
  • 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.
  • 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 different cartridge may be used in the kit. This does the same job as the Watts WCBFF975. They're just different brands.

  • 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


  • Watts canister containing 500ml of A8210 OneFlow anti-scale media / 4.5 x 10"
  • Chemical free scale prevention and protection - converts hardness minerals to harmless, inactive microscopic crystals.
  • Virtually maintenance free - just replace your OneFlow cartridge every 1-2 years.
  • No control valve, no electricity and no wastewater.
  • OneFlow is not a water softener. It does not add chemicals into your water or remove the beneficial minerals. 

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. 

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 Moby Taste and OneFlow Hard water filter the 5 micron carbon block cartridge goes first in the sequence, followed by the canister containing 500ml of Watts A8210 OneFlow anti-scale media.


* 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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Related Items

  • Moby Taste and OneFlow Hard Water Filter Replacement Cartridges


    Moby Taste and OneFlow Hard Water Filter Replacement Cartridges

    Free UK P&P on all our replacement water filter cartridges. Carbon block cartridge and Watts OneFlow cartridge.



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