Welcome everybody to today's session regarding the changes with the 2025 edition of the AS 3500 series.
Today, we'll be looking at a few of the major changes in this edition for Parts 1 and 4 of AS 3500 series.
There are new requirements and classes for flexible hose assemblies, minor changes in backflow prevention for AVBs or atmospheric vacuum breakers, new requirement for isolation valves when installing flexible hose assemblies which are connected to a mixer valve, tap outlet, or cistern, new requirements for the connection of miscellaneous devices or appliances connected to water supply, and a few editorial changes to make the standard easier to read.
Here is a list of the normative reference standards called up in the relevant clauses of this part of AS 3500 series.
Just a reminder that while working with the reference standards, the term of normative is expressed in a mandatory application. And informative is for information and guidance.
Clause 2.3.1 now expands on the requirements by including 110 millimetres in the clause to accommodate for the differences in how some pipe sizes are described.
Some pipe sizes are described as internal, external or nominal, for example.
So for pipe size range between 100 millimetres to 110 millimetres – the allowable operating pressure remains the same as the previous 2021 edition of being 1200 kpa or 1.2 megapascals at 20°C
And pipe size larger than 110 millimetres must accommodate the operating pressure and temperature for the system.
Be sure to also refer to the manufacturer's installation specifications and scope of use when carrying out installations.
The installation method of such pipes and fittings should avoid exposure to excessive heat for any appliance.
Clause 2.3.2.1 goes over the accessibility requirements to only be allowed for use in accessible locations, and not be buried.
The term accessible is defined in the standards as “capable of being reached for the purposes of inspection, maintenance, repair or replacement, but may first require removal of an access panel, cover, door or similar obstruction”.
There are new classification requirements when considering the installation of flexible hose assemblies – now located in clause 2.3.2.2, and also in an associated table.
These requirements are related to the hose class, not the building class.
Depending on the class of the flexible hoses, certain requirements may apply and be specific in such situations.
For class one (hoses), they are end of the line flexible hose with open ends having no isolation devices after the inlet of the hose.
Specifically for class one (flexible hoses), it must only be used for dynamic pressure applications and not for static pressure applications.
For classes two or three flexible hoses are only to be used to connect between two fixed points.
In this instance and with this class, it is used for static pressure.
A few points here provide more information on what are fixed points, such as being between a pipe and fixture, fitting, valve or tap.
For class four (flexible hoses), they are end of line flexible hoses with an integral stop valve or the like, and these are used for static pressure applications.
Here is the classification table 2.3.2.2 providing a snapshot of the requirements of flexible hose assemblies, depending on the class, application, and the limitations associated with these installations.
There is a new clause here, clause 2.3.2.3, regarding the operational temperature range of flexible hose assemblies, also covering applications where the hose may be submerged.
You must only use a hose assembly rated for its intended application.
For hoses that are rated in applications up to 70°, it is either marked with 70°C or an “L”.
For hoses that are rated in applications up to 90°, it is either marked with 90°C or “H”.
In submerged applications, hoses must be rated to be used and marked with an “S”.
Flexible hoses that are marked with “S” are rated for submersion.
These hoses may have a protective external coating or additional resistance to corrosion.
A situation where you would use the flexible hose marked with an “S” would be in the top entry system for a water closet, as it's going to be sitting in water.
It is important to ensure the correct hoses are used as they are relevant in systems where pressure ratings are critical for safety and performance.
Always refer to manufacturer's specifications for further information on the limitations of the hose application.
Clause 2.3.3 is a new clause which expands on the requirements of semi flexible hose assemblies.
Similar to the requirements of flexible hoses.
Semi flexible hoses must ensure the following for compliance. It is only to be used in accessible locations, not to be buried, or not to be used where there is expected repeated movement.
Semi flexible hoses are commonly called ”semi rigid hoses”.
A few examples of where these connections may occur such as connections to appliances, tapware, water heaters and such.
There are a few updates to be aware of regarding backflow prevention devices in clause 4.4.
Atmospheric Vacuum Breakers, commonly called AVB for short, has been reclassified from being non-testable devices to – registered testable devices in the 2025 edition.
This information is found in Table 4.4.1.
The hazard rating remains the same, being suitable for high, medium or low hazard risks.
As this reclassification lists AVBs as being testable devices, it must be commissioned and tested as is required by the standard of ASNZS 2845.3 – this is the standard that applies for field testing of testable devices and should only be used where there is device registration and certification.
Clause 4.6.1 has some changes where, other than fire services, AVBs must have line strainers when backflow prevention device is fitted.
They should also not be installed with downstream isolating valves.
Backflow devices fitted with test taps need to ensure accessibility – this is in clause 4.6.2.2.
This is for testing purposes if the setup requires dismantling when maintenance is to be carried out.
Clause 4.6.3.3 has now removed AVBs and included its requirements in the list of testable devices.
There is an update in clause 5.4 for the locations of isolating valves.
This clause now requires isolation valves to be installed immediately before each flexible hose assembly that is connected to a mixer valve, a tap outlet or cistern.
This is in sub clause (l) of clause 5.4.2.
This applies to circulatory piped plumbing systems.
A new clause 5.20 goes over the requirements where miscellaneous devices and appliances are connected to drinking water supply.
Pipe work and fittings must be sized to provide adequate water supply, appropriate backflow prevention devices, isolation valves and pressure limiting requirements where required.
The installation of the pipe work and fittings must allow for the disconnection and maintenance of those devices and/or appliances.
An example of a miscellaneous device or appliance could be a dental console.
Clause 9.1 goes over the requirements of non-drinking water services.
Ensure to check the National Construction Code, the Plumbing Code of Australia, regarding the limitation of the use of non-drinking water.
Practitioners must ensure there is consultation with the relevant network utility operator as they may stipulate that the non-drinking water metre assembly is installed in a different location.
For more information, please refer to Figure 9.1 which shows the typical layout of a non-drinking water installation.
Now we'll look at the changes in Part 4 of the AS 3500 series changes for 2025 edition.
There are new requirements for the use of flexible hose assemblies and heated water installations,
requirements for isolation valve installation before each flexible hose that is connected to a mixer valve or tap outlet, and editorial changes that make the standard easier to read.
Similarly to Part 1 – clause 2.3.1 covers the provision where different descriptive methods of pipe size of 100 millimetres could be internal, external or nominal in diameter.
The size has been increased from 100 millimetres to 110 millimetres.
This new clause in 2.3 of Part 4 goes over the requirements of accessibility, and its limitations for flexible hose assemblies.
The term of being accessible is defined further in more detail as you can see here.
The requirements of flexible hose assembly classes are once again covered in this part of the 2025 edition of Part 4.
Depending on the class of flexible hose selected, the application must be suitable for its intended installation.
Ensure the appropriate class of hose is used for the correct application.
The classification table 2.3.2.2 is once again provided here to provide a snapshot of the requirements of flexible hose assemblies, depending on the class, application, and the limitations associated with those installations.
Just like in Part 1 – there is a new clause here, clause 2.3.2.3 regarding the operational temperature range of flexible hose assemblies, also covering applications where the hose may be submerged.
You must only use a hose assembly rated for its intended application.
Hoses must be marked with the appropriate temperature rating or the coinciding letter to suit the application.
Semi flexible hoses, commonly called “semi rigid hoses”, are once again covered in this section.
Ensure where semi flexible hoses are selected for use, that it meets the following requirements.
Some updated changes now applying clause 5.4 for the protection against damage from leaking water.
Clause 5.4.2 now states that all unconcealed water storage tanks must be installed with safe trays and safe wastes, unless it meets the following requirements.
That the unconcealed water storage tank inside buildings is on or above a floor surface that is impervious to water and suitably drained, or the water heater is fitted with a leak protection device such as a mildred valve.
Safe trays are not required for storage water heaters up to 13.5 litres in capacity or instantaneous and continuous flow systems.
Similar to Part 1 – Clause 10.10.2 in Part 4 once again includes the addition to the location of isolating valves.
It states that an isolation valve must be installed immediately before the flexible hose assembly connected to a mixer valve or tap outlet.
This applies to circulatory pipe plumbing systems.
And that concludes our session of the 2025 updates to Parts 1 and 4 of the AS 3500 series.
If you do have any questions or want further information, please email us at plumbingtechnicaladvice@bpc.vic.gov.au.