Wastewater Reclamation Unit Safe Work Method Statement

Wastewater reclamation installations must comply with several Australian Standards and regulatory frameworks. AS/NZS 3500.1 (Plumbing and Drainage - Water Services) provides core requirements including backflow prevention, pipe materials, and installation methods for greywater systems. This standard specifies purple pipe colour coding for recycled water distribution, prohibition of cross-connections with potable water, and requirements for system labelling. AS/NZS 1547 (On-site Domestic Wastewater Management) applies to greywater treatment and disposal systems providing guidance on design, installation, and management. AS 2419.1 (Fire Hydrant Installations) becomes relevant if recycled water supplies fire services. State and territory health departments administer additional regulations governing water quality standards, system approval processes, and public health protection requirements. Many local councils have specific greywater policies requiring approval before installation. Environmental Protection Authority regulations may apply particularly for commercial systems. Plumbers must research all applicable standards and regulations for their jurisdiction and obtain necessary approvals before commencing installation to ensure legal compliance and system approval.

Greywater is defined as wastewater from domestic activities excluding toilet waste (blackwater). Greywater typically includes water from showers, baths, hand basins, and laundry facilities. However, regulations distinguish between different greywater quality levels. Light greywater from showers and basins generally has lower contamination levels than laundry water particularly if nappies are washed. Kitchen sink water is often excluded from greywater systems due to grease, food particles, and potentially higher bacterial loads, with many jurisdictions classifying kitchen waste as requiring treatment equivalent to blackwater. Washing machine water quality depends on washing activities. Water quality and treatment requirements vary based on greywater sources and intended end use. Greywater reused for subsurface irrigation requires less treatment than water used for toilet flushing where human contact is more likely. Australian guidelines recommend treatment appropriate for end use with higher treatment levels for applications with potential human contact. System designers must clearly identify greywater sources and ensure treatment capacity matches both volume and contamination level. Regulations prohibit combining greywater with blackwater in treatment systems. When planning wastewater reclamation installations, verify local regulations regarding acceptable greywater sources and required treatment levels for intended applications.

Wastewater reclamation systems require regular maintenance to ensure continued safe operation and water quality compliance. Maintenance schedules vary by system type and manufacturer but typically include filter cleaning or replacement every 1-6 months depending on loading, inspection and cleaning of settlement tanks quarterly or more frequently, testing and replenishment of disinfection chemicals monthly or as consumed, cleaning of UV quartz sleeves quarterly and lamp replacement annually, pump inspection and servicing annually including seal inspection and impeller cleaning, and comprehensive water quality testing quarterly or as required by regulations. Many regulations require licensed plumbers to perform maintenance involving plumbing system modifications or disconnection of water services. Filter replacement and routine cleaning may be performed by property owners following manufacturer instructions. Chemical system servicing should be performed by persons with appropriate chemical handling training. Some jurisdictions require annual inspection and water quality verification by licensed professionals for systems used for toilet flushing or other higher-risk applications. Documentation of maintenance activities is typically required including service dates, work performed, water quality results, and any defects identified. Failure to maintain systems properly can result in system failure, water quality deterioration creating health risks, and potential regulatory enforcement. Property owners should establish maintenance contracts with qualified service providers ensuring regular servicing occurs and documentation is maintained.

UV disinfection and chlorine-based disinfection represent the two primary disinfection methods for greywater reclamation with distinct advantages and considerations. UV disinfection uses ultraviolet light at 254-nanometre wavelength to inactivate microorganisms without adding chemicals to water. Advantages include no chemical handling, storage, or residual chemicals in treated water; effective against wide range of bacteria, viruses, and protozoa; no taste or odour added to water; and environmentally friendly with no disinfection by-products. Limitations include no residual disinfection protection after UV treatment so bacterial regrowth can occur in storage; effectiveness depends on water clarity with turbidity reducing UV transmission; requires regular lamp replacement typically annually; and requires electrical power continuously. Chlorine-based disinfection uses sodium hypochlorite liquid or calcium hypochlorite tablets introducing free chlorine to water which oxidises and destroys microorganisms. Advantages include providing residual disinfection protecting water quality in storage; effective against wide microorganism range; relatively simple systems; and continues working after initial application. Limitations include requiring chemical handling, storage, and regular replenishment; potential for taste and odour in treated water if residual too high; producing disinfection by-products; requiring monitoring to maintain correct dosing; and potential safety hazards from chemical exposure. System selection depends on application requirements, maintenance capabilities, and regulatory requirements. Many high-quality systems combine both methods using UV primary disinfection with low-level chlorine residual for storage protection.

Cross-connection prevention is absolutely critical in wastewater reclamation installations as contamination of potable water with greywater creates serious public health risks. Plumbers must implement multiple barriers preventing cross-connection. Physical separation requires using purple-coloured pipe exclusively for recycled water distribution with no exceptions, maintaining complete physical separation between recycled and potable water pipework with minimum 300mm clearance where pipes must cross, and using different pipe sizes for recycled water to prevent accidental connection. Clear identification includes labelling all recycled water pipes at minimum 3-metre intervals with 'RECYCLED WATER - NOT FOR DRINKING' signage in durable materials, installing permanent labels at all outlets and connection points identifying recycled water, and using purple-coloured fixtures where feasible to distinguish recycled water taps. Backflow prevention requires installing testable backflow prevention devices (RPZ valves) on any potable water connection to greywater systems, annual testing of backflow devices by licensed tester with documentation maintained, and ensuring backflow devices installed in accessible locations allowing testing. Installation verification includes independent pressure testing of recycled and potable systems confirming no interconnection, photographic documentation showing separation and colour coding, and commissioning inspection confirming no cross-connection pathways exist. Client education must explain recycled water safety, purple pipe identification system, prohibition on connecting potable fixtures to recycled water, and importance of hiring qualified plumbers for any future modifications. Documentation including detailed as-built drawings showing complete system layout must clearly distinguish recycled and potable systems for future maintenance workers. Any cross-connection discovered must be immediately rectified and reported to relevant authorities.

Water quality testing requirements for greywater reclamation systems depend on intended water use and applicable regulations. Common parameters include turbidity (cloudiness) which should typically be below 5 NTU for effective disinfection and aesthetic quality; total coliform and E. coli bacteria levels with limits varying by use—toilet flushing typically requires below 10 CFU/100mL E. coli, irrigation may allow higher levels; residual disinfectant (chlorine) if chemical disinfection used, typically maintained at 0.2-1.0 mg/L free chlorine for distribution system protection; pH should be maintained between 6.5 and 8.5 for effective disinfection and pipe protection; and suspended solids which should be minimised to prevent filter clogging and maintain disinfection effectiveness. Some regulations require additional testing including biochemical oxygen demand (BOD), chemical oxygen demand (COD), and specific pathogen testing. Testing frequency varies by jurisdiction and use—commissioning typically requires comprehensive testing before system approval, quarterly or biannual testing may be required for ongoing operation particularly for higher-risk applications like toilet flushing, and annual testing is minimum for most systems. Testing should be performed by accredited laboratories using approved methods. Many jurisdictions provide specific greywater quality guidelines—for example, some states require Class A recycled water standards for certain applications while others specify greywater-specific standards. System operators must understand applicable standards for their jurisdiction and intended use. Documentation of water quality results must be maintained and may be required for regulatory compliance verification. If water quality testing reveals non-compliance, system operation may need to be suspended until corrections are made and retesting confirms compliance.