As a water supplier, the Council must provide wholesome potable water to its consumers. Potable means the water is safe for human consumption.
The water supply can be contaminated within the watermains if water is drawn back into the mains from a consumer's property. This event is known as "Backflow" and can be the result of one of the following occurences:
Back siphonage - when the water pressure in the supply is less than the pressure in the consumer's piping system. This may be the result of a burst water pipe, the water being shutoff or a fire hydrant being used.
Back pressure - when the pressure in the consumers piping system is more than that of the supply. This can occur when header tanks or booster pumps are used within a property.
Legislation requires Council specifically to take steps to minimise the risk of backflow to the system. All properties are assessed to determine the level of risk they pose to the water supply in the event of a backflow event occuring. There are 3 levels of risk currently assigned.
Council Policy on Backflow PreventionThat all new non-domestic (Farming, Commercial, Industrial etc) connections are fitted with an approved backflow prevention device appropriate for the level of risk associated with the activities undertaken within the property.
That all new domestic connections and any new non-domestic connections that are not assigned as a medium or high risk shall have a non-testable double check valve installed on the connection.
That a programme of investigation be progressively undertaken to assess all existing connections and where required, have the appropriate backflow device installed.
Draft Backflow Code of Practice
A Backflow Special Interest Group, in conjunction with the New Zealand Water and Wastes Association (NZWWA), have produced a draft Code of Practice on Backflow Prevention. This first draft is currently being evaluated and it is likely that, once complete, this document will be adopted into existing Bylaws.
Levels of Risk
There are 3 levels of risk currently assigned to properties:
High Risk - where contamination of the supply by backflow may result in serious health problems or death.
Medium Risk - where contamination of the supply by backflow may result in minor health problems and/or cause aesthetic problems (ie taste, smell, colour contamination).
Low Risk - where contamination of the supply by backflow may result in minor aesthetic problems (ie taste, smell, colour contamination).
Consumers ResponsibilitiesAll consumers are responsible for preventing water returning to the public mains. Where any piping system is used or connected in such a manner as to be a possible source of contamination to the water supply, the consumer shall protect the service connection at the point of supply with an appropriate and approved backflow prevention device.
The device must be tested annually by a registered Independently Qualified Person, or IQP. The testing and maintenance of the device is the responsibility of the property owner.
Laws Relating to Backflow PreventionCurrent legislation that relates to backflow prevention include the following:
Public Health Act 1956
Water Supplies Protection Regulations 1961 Local Government Act 1974
Rotorua District General Bylaw 1980
Building Act 1991
Building Regulations 1992
Health and Safety in Employment Act 1992
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