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Building Commission NSW has issued guidance on plumbing and drainage compliance for prefabricated modules, following instances where units were installed or connected without the required certification.
The advisory note, updated on 6 November 2026, addresses the certification obligations applying to prefabricated plumbing modules manufactured in NSW, interstate and overseas.
The guidance applies to developers, builders, module manufacturers, licensed practitioners and plumbing contractors. It identifies compliance requirements under the Plumbing and Drainage Act 2011, particularly where factory-completed plumbing systems are subsequently connected to services on a construction site.
Building Commission NSW says it has identified instances where prefabricated modules have been installed or connected without the required NSW Certificate of Compliance (CoC) or WaterMark certification.
The advisory note distinguishes between modules manufactured within NSW and those produced elsewhere.
Different requirements for local and imported modules
Under the guidance, prefabricated plumbing modules manufactured interstate or overseas must hold current WaterMark certification before they can be installed or connected to plumbing and drainage systems in NSW.
Modules manufactured and installed within NSW have two compliance pathways. They may hold WaterMark certification, or the plumbing and drainage work can be undertaken as regulated work under NSW legislation.
Where the regulated-work pathway is used, practitioners must submit a Notice of Work, arrange mandatory inspections with the relevant local plumbing regulator and issue a Certificate of Compliance upon completion.
Plumbing and drainage work undertaken within a NSW manufacturing facility must also be covered by a CoC issued by the licensed NSW plumbing contractor responsible for that work.
Irrespective of the manufacturing location, a separate CoC is required when a prefabricated module is connected to water supply, sewerage, network utility infrastructure or onsite wastewater management systems.
Factory certification and onsite compliance
The distinction between factory certification and onsite connection requirements has practical implications for modular housing manufacturers and prefabricated bathroom pod suppliers operating across state borders.
Manufacturers supplying NSW projects must establish the applicable certification pathway before installation, particularly where modules incorporate plumbing systems completed at an interstate or overseas facility.
The advisory does not introduce a new certification framework. Rather, it clarifies existing obligations and identifies compliance failures encountered by the regulator.
Building Commission NSW warns that connecting non-compliant modules may constitute an offence and result in enforcement action, including disconnection of plumbing and drainage services until the necessary documentation and approvals are obtained.
The guidance reinforces the need for manufacturers, builders and licensed plumbing contractors to coordinate certification responsibilities across factory production and onsite installation.
Source: NSW Government
