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WD Aqua-Flo - A Water Line Freeze Protection System

The WD Aqua-Flo System - How it works

WD Aqua-Flo is a failsafe, energy saving appliance that incorporates proven principles that ensure the prevention of water service lines from freezing. Despite the problem and cost involved in the continuous bleeding of water through each service line, it is a fact that flowing or moving water does not freeze readily.

WD Aqua-Flo maintains a continuous flow of water 24 hours a day. This is accomplished by a BLEED, CAPTURE and RETURN method. Water is constantly flowing, but not from the tap into the sewer system.

Water is BLED from the house or municipal supply through an orifice into the holding tank. The water level in the tank increases and the trapped air is released through an air release valve and/or an activated carbon air filter. At a predetermined tank level, a pneumatic switch is tripped. The motor starts and the pump forces the water through a check valve into the stream ahead of the orifice and then into the service line and water main. The orifice bleeds the water at a rate of about 1 litre per minute. The filling time is approximately 45 minutes, and the pump down time is about 4 minutes. One cycle lasts about 45 minutes. This cycle is repeated over and over again in a closed, sterile system.

The CAPTURE and RETURN characteristics of Aqua-Flo must be emphasized because these features uniquely make WD Aqua-Flo a foolproof system. As the water BLEEDS into the tank, it absorbs some heat from the surrounding air. Combined with the friction in the pump down cycle, the water temperature may increase by 2 to 4 degrees Celsius. When this warmer water is pumped back at a high velocity, any annular formations of ice that may begin to form in the BLEED cycle are scoured off so that each BLEED cycle begins with as full a diameter of warmer water as possible. It is this phenomenon that eliminates the likelihood of a water service line freezing up with WD Aqua-Flo.

Simply stated, this amazing appliance maintains constant flow of water through a single service line and returns the water into the system through the same water line without any loss.

During periods of electrical or mechanical failure, flow is still maintained by OVERFLOWING the tank into a drain. This is WD Aqua-Flo’s back up system, something that no other freeze protection system has.

Advantages of the WD Aqua-Flo System

For the Homeowner:

  • Positive protection against freeze up without a heavy burden on municipal systems

  • Can be installed in any house - old or new

  • Easy indoor installation will save you money and aggravation with water line freeze up

  • No costly excavation required

  • Low initial cost

  • Low operating cost

  • Costs less than heat tracing installations for new housing

  • No costly power bill as with heat tape

  • No wasted water

  • Extended pump and motor life due to low operation time

  • Maintains protection during times of electrical or mechanical failure

  • Has a built in back up system

  • Heat absorbed in house is returned to the municipal system saving municipal heating costs

  • Can be a standard “built in” system on all new mobile homes and recreational vehicles

  • Investments may be recouped in as little as a one year period

For a Municipal Authority: 

  • Greater water consumption often requires expanded headworks, larger reservoirs and larger supply mains to supply an ever increasing demand for water. Indiscriminate bleeding places a burden on sewer treatment facilities particularly during the winter months. A water and sewer system designed with a “bleed and return” system as WD Aqua-Flo could eliminate costly water and sewer upgrading projects

  • As water bleeds into holding tank in a warm home, it absorbs heat and is returned to the water main, this would help reduce municipal heating costs where water must be heated before distribution

  • There is less water to treat, so expensive savings can be realized by municipalities

  • A significantly lesser amount of cold diluted waste water needs to be treated. It is easier and cheaper to treat normal strength warmer sewage than colder dilute sewage.

  • There is less danger of frozen sewer lines as well

  • WD Aqua-Flo is the sensible answer to water conservation and resultant energy and cost savings

  • WD Aqua-Flo increases the storage capacity of any water system. WD Aqua-Flo is as close as anyone could come to achieving a perpetual motion water pressure system because individual units and households help pressurize and maintain water pressure in the entire system

Technical Data - Model AF-6VB

  • TANK: Opaque polyethylene; minimum 1/4” wall thickness; 18” x 18” x 25” high (460mm x 460mm x 640mm)

  • PUMP: Proco - rotary vane type pump

  • MOTOR: 1/2hp; 1725 RPM; single phase, integral switching; resilient base mounted; full load 8-1/4 Amps; Class B insulation; Amb. 40 degrees Celsius; thermally protected MA

  • MOTOR CONTROL: 15 Amp Robertshaw Controls; pneumatic-water column switch

  • HOSES: 1/2” inside diameter nylon reinforced; 200 PSI at 40 degrees Celsius; 3/8” polyethylene

  • BACKFLOW PREVENTER VALVE: Bronze #125 - 3/8” male pipe

  • MAXI-FLO CHECK VALVE: Broze #600 Watts - 1/4” male pipe

  • ORIFICE: 1.1 to 2 litres/minute flow rate; 1/4 to 1/2 gallon/minute flow rate

  • RESERVOIR CAPACITY: 74 Litres (16.6 gallons)


  • CYCLE TIME: Bleed - approximately 45 minutes; Pump Down - approximately 3-4 minutes

  • POWER CONSUMPTION: Approximately 1 KWH per day; 30 KWH per month


C.S.A. Report #LR 52649 is available on request.

The WD Aqua-Flo system of waterline freeze protection has been studied and evaluated by the health inspection agencies of several provinces and territories. Approvals or permission to use WD Aqua-Flo from the provinces and territories contacted have been received. A list of these is available on request.

WD Aqua-Flo Guarantee

We warrant that the WD Aqua-Flo appliance to be free from defects in workmanship and materials for a period of twenty-four (24) months from the date of delivery to the original retail purchaser. Our obligation under this warranty does not cover labour and/or freight charges and is limited to supplying to the owner a replacement for any part becoming defective under normal use and service following proper installation.

This warranty is in lieu of all warranties expressed, implied, or statutory and we neither assume nor authorize any persons to assume for us any other obligation or liability in connection with the sale of the WD Aqua-Flo appliance.