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Made in the UK

Moby OneFlow Hard Water Filter

Contains Watts OneFlow TAC Media. The best anti-scale system on the market.






Solve your scale problems with our OneFlow cartridge.

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

This is an undersink water filter and when fitting allow for a minimum of H 38cm x W 40cm x D 18cm.

This is not a water softener. The Moby 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.

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.

Your kit will include:

  • 1 x big blue filter housings
  • 1 x white housing bracket
  • 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:

  • 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
  • Tested and certified under NSF / ANSI standard 42 for materials only.
  • 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 waste water.
  • OneFlow is not a water softener. It does not add chemicals into your water or remove the beneficial minerals. 
  • Replacement Moby OneFlow cartridges are £183.99 and we'll email you every 6 months to remind you to check your filter performance. 

Note that OneFlow starts working right away, but there will be residual limescale in your water pipes that can take up to three months to clear before you start noticing the difference. In addition, the efficiency of OneFlow is greater if the water is filtered for chlorine first. See the Moby Taste and OneFlow for more details.

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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