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OneFlow Series OFRES – Residential Whole House

Series OFRES

Whole House OneFlow ® Residential Anti-Scale Systems

Connection Sizes: 1″ (25mm) MNPT

Flow Rates: Up to 16 gpm (60 lpm)

OneFlow Residential Whole House Anti Scale SystemOneFlow® 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 alternative to water softening (ion exchange) or scale sequestering chemicals.


  • 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
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  • 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
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*Always install OneFlow® Residential systems before the water heating device.

Note: Do not use with water that is microbiologically unsafe or of unknown quality without adequate disinfection before or after the system.

Feed Water Chemistry Requirements
pH6.5 to 8.5
Hardness (maximum)75 grains (1282 ppm CaCO3)*
Water Pressure15psi to 100psi (103 kPa to 6.9 bar)
Temperature40°F to 110°F (5°C to 43°C)
Chlorine< 2ppm
Iron (maximum)0.3 mg/l
Manganese (maximum)0.05 mg/l
Copper< 0.1 mg/l
Oil & H2SNone allowed
PolyphosphateNone allowed
Silica (maximum)10 ppm

*Note: These systems prevent hardness related scale formation inside the plumbing system of the home at influent hardness levels of 75 grains per gallon of calcium carbonate and less. Due to variances in water chemistry certain aesthetic conditions external of the plumbing system may not be attained. Water known to have heavy loads of dirt and debris should be prefiltered. Recommended PWFILSED- BB-10-20M-PMT PWHSG-AST-BB-10-1-PR. Copper lines need to be passivized for a minimum of 4 weeks before placing unit into service. Not for use on closed loop systems.

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ModelConnection SizeMineral Tank SizeMedia LtrsMaximum Service Flow (GPM)*Pressure Drop (PSI)**Floor Space (LxWxH)
OFRES-08351" MNPT8" X 35"28<1513" X 9" X 40"
OFRES-09351" MNPT9" X 35"312<1513.5" X 10" X 40"
OFRES-10351" MNPT10" X 35"416<1514" X 11" X 40"

*Exceeding maximum flow can reduce effectiveness and void warranty.

**Pressure drop at maximum service flow rate.

OFRES Tank SizeReplacement Media

  • OFRES-0835RM Media should be replaced every 3 years
  • OFRES-0935RM Media should be replaced every 3 years
  • OFRES-1035RM Media should be replaced every 3 years

Note: Maximum service flow rate is for intermittent use only and is not to be interpreted as continuous service flow rate capability. These systems are designed to treat the domestic water used in a single family dwelling. For higher volume applications please contact your Watts representative.


Independent scientific testing has confirmed Template Assisted Crystallization (TAC) technology provides scale reduction of over 95+%. Testing was conducted under protocol based on DVGW W512 test to access control of scale formation.

Dimensions – Weights

OFRES-08358" x 35"37"37"40"12"199
OFRES-09359" x 35"37"37"40"12.5"2310
OFRES-103510" x 35"37"37"40"13"2511