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Made in the USA

OneFlow OFRES-0935 Hard Water Filter

The OFRES-0935 is a large scale hard water filter for your house with a flow rate of 45 litres per minute. Free UK standard delivery on all hard water filters.



Product SKU: WWQ-OFRES-0935

UPC/EAN: 098268743869


Certified by WQA

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.

Connection Sizes: 1" (25mm) MNPT

Flow Rate: 12 gpm (45 lpm)

Change the media once every two to three years. 

OneFlow® Residential Anti-Scale Systems provide a home with protection from internal hardness related scale formation on plumbing surfaces. Water using appliances and plumbing fixtures also enjoy a longer lifespan because hardness scale build up on internal parts no longer occurs. These systems are specifically designed for residential applications. OneFlow® Residential systems should be installed at the point-of-entry to a home to treat both the hot and the cold water.

OneFlow® Residential systems prevent scale by transforming dissolved hardness minerals into harmless, inactive microscopic crystal particles. These crystals stay suspended in the water and are passed to drain, thereby having a greatly reduced ability to react negatively like dissolved hardness does. These systems require very little maintenance, no backwashing, no salt, and no electricity. Typical hardness problems, especially build-up of scale in pipes, water heaters, boilers, fixtures, and appliances are no longer a concern.

OneFlow® Residential systems are not water softeners or chemical additives (like anti-scalants or sequestrants). They are scale prevention devices with proven third party laboratory test data and years of successful applications. OneFlow® Residential systems are the one water treatment device that effectively provides scale protection in the home and are a great salt-free alternative to water softening (ion exchange) or scale sequestering chemicals.

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


  • Chemical free scale prevention and protection – converts hardness
  • minerals to harmless, inactive microscopic crystals making OneFlow® an effective alternative technology to a water softener for the prevention of scale due to water hardness
  • Virtually maintenance free – No salt bags or other chemicals
  • to constantly add
  • No control valve, no electricity and no wastewater
  • Uses environmentally friendly “green” technology
  • Improves efficiency of all water using appliances – both hot†
  • and cold
  • Simple sizing & installation
  • Perfect system for towns or communities where water softeners
  • are banned or restricted
  • OneFlow® - Residential systems do not remove minerals or
  • add sodium to the water supply
  • OneFlow® - Residential systems can be installed as a pretreatment
  • to reverse osmosis (OneFlow® should be the last stage in treatment unless a point-of-use system is being used downstream.)
  • Systems include a bypass valve for a simplified installation

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. 

Does the media in a OneFlow Ofres system need to be replaced?

Yes, OneFlow media in a tank based Ofres system needs to be replaced every 2-3 years. You can find the loose media here.

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