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Backflow Protection - Explained Simply

The flow of water or other liquids, mixtures, or substances into the distributing pipes of a potable supply of water from any sources other than its intended source.  See Back-Pressure Backflow, Back-Siphonage.
Potable Water
Water suitable for human consumption.  Potable water is connected to all sanitary fixtures, water heaters, food preparation areas and other typical water supply connections used for human consumption. 
Non-Potable Water
Water unsuitable for human consumption. 
Contamination of the potable water supply system may affect:- 
  • The health of individuals living or working within a property or
  •  Flow back into the town water supply distributing that contamination to other properties in the same location. 
Back-Pressure Backflow
The backflow due to an increased pressure above the supply pressure, which may be due to pumps, boilers, gravity, or other sources of pressure.   Back-pressure backflow is generally not applicable to bidet seats or attachments because they are not connected any other sources of pressures that are greater than the supply pressure.
The flowing back of used, contaminated, or polluted water from a plumbing fixture or vessel into a water supply pipe due to a pressure less than atmospheric in such pipe.  Back-siphonage is applicable to bidet seats and attachments, which can be prevented using a backflow prevention device.
Is an actual or potential connection between the potable water supply system and a non-potable water supply source.  Cross-connection (or Backflow) from a toilet can ONLY happen when:
  1. the toilet waste is blocked and the toilet bowl full of contaminated or ?fouled? water, and
  2. the nozzle or spray tip is stuck in the extended position and is submerged in the ?fouled? water, and  
  3. the water supply valve (stop-tap) is opened; and
  4. the water supply line is disrupted by local fire or other reasons.   
Backflow can be prevented or reduced by either shutting off the water supply at the valve (or stop-tap in the instance of a toilet) or by a properly installed backflow prevention device.
Backflow Prevention Device
There are various types of backflow prevention devices available.
One type of backflow prevention device is a dual check valve which is designed for use under constant pressure and provides protection where a potential low level health hazard exists.The Australian Standard for bidet seats, ATS 5200.051 requires bidet seats and attachments to have approved backflow protection.  A backflow prevention device certified to Australian Standard AS/NZ 3500.1 can provide suitable backflow protection.   
All products which connect to a domestic (potable) water supply;
  • have been tested and are certified to the appropriate Australian Standard and
  • have a WaterMark Licence, and
  • have complying backflow protection already fitted or
  • have a complying backflow prevention device included in the package as sold, and
  • come with full installation instructions and contact details for technical advice or service.
  • The details of the WaterMark Licence and the Licence Number are clearly labelled on every product. 
A WaterMark with Licence Number is your only certain assurance that a bidet product has been tested and is certified to the appropriate Australian Standard.

Back Flow Prevention device $25 ex GST