Rainwater and storage tanks on commercial properties, apartment blocks and strata buildings are not a set-and-forget installation. They require regular professional cleaning and maintenance to keep the stored water safe and to comply with NSW public health and building regulations.
If you manage a commercial building, a strata complex or a multi-dwelling residential property, understanding your obligations around water tank maintenance is essential. Here is what you need to know.
What Regulations Apply to Commercial Water Tanks in NSW?
Commercial and multi-residential water tanks in NSW fall under several overlapping pieces of legislation and guidance:
- Public Health Act 2010 (NSW): Places a duty on building owners and operators to take all reasonably practicable steps to ensure water supplied to their premises is safe for the intended use (drinking, sanitation, food preparation).
- NSW Health Guidelines for Managing Water Quality in Buildings: Provides specific guidance on inspection, cleaning and maintenance intervals for water storage systems in buildings.
- Australian/New Zealand Standard AS/NZS 3500: Sets requirements for plumbing and drainage systems including cold water storage tanks.
- Local Council Requirements: Many councils have their own conditions attached to development approvals that specify tank maintenance obligations for commercial and strata properties.
In practice, this means commercial water tanks should be inspected at least annually and cleaned whenever contamination, sediment buildup or biological growth is detected, or at minimum every 2 to 3 years.
Who Is Responsible for Commercial Tank Maintenance?
The responsibility sits with the owner of the building or the body corporate in a strata arrangement. In practice, this responsibility is often delegated to a strata manager or facility manager, but the legal obligation remains with the building owner or body corporate.
If a tenant or resident becomes ill due to contaminated water from a poorly maintained storage tank, the building owner or body corporate may face significant liability claims on top of any regulatory action.
How Often Should a Commercial Water Tank Be Cleaned?
The appropriate cleaning frequency for a commercial tank depends on several factors:
- Intended water use: Tanks supplying drinking water need more frequent attention than tanks used for irrigation or toilet flushing only.
- Tank size and turnover: Large tanks with slow water turnover develop more sediment and biological growth than tanks that cycle through their volume frequently.
- Environmental factors: Tanks in areas with heavy leaf fall, bird activity or dust exposure need more frequent inspection and cleaning.
- Tank material and age: Older concrete tanks with deteriorating internal surfaces require more frequent attention than modern poly tanks.
As a general guide for commercial properties:
| Tank Use | Recommended Cleaning Interval |
|---|---|
| Potable (drinking) water | Every 1 to 2 years |
| Non-potable (toilet, irrigation) | Every 2 to 3 years |
| Fire water storage (AS1851) | Per AS1851 schedule (annual inspection minimum) |
| Cooling tower makeup water | Per cooling tower risk management plan |
What Does a Commercial Tank Clean Involve?
A professional commercial tank clean is more involved than a standard residential job. For multi-storey buildings or large commercial sites, the process typically includes:
- Isolation of the tank from the building’s water supply to ensure no contaminated water enters the system during cleaning
- Full pump-out of remaining water
- High-pressure internal wash and removal of all sediment, sludge and biofilm
- Inspection of all inlet, outlet and overflow fittings
- Check of ball valves, floats and any automatic refill systems
- Disinfection treatment if required (chlorination or UV)
- Written inspection report documenting the condition of the tank and any defects found
The written report is important. If you are a strata manager or building owner, you should keep copies of all tank inspection and cleaning reports as part of your building’s maintenance records. These records are essential if you are ever required to demonstrate compliance to a council inspector or a court.
Underground and Basement Tanks on Commercial Sites
Many commercial and strata properties have underground or basement water storage tanks. These present additional challenges for maintenance and cleaning, including confined-space access requirements and the need for specialist pumping equipment.
Underground water tank cleaning for commercial sites requires contractors with confined-space certification and the appropriate equipment to work safely in below-ground environments. Not all tank cleaning operators have this capability, so confirm before booking.
Large-Scale Commercial Tank Installations
If your property’s tank system has reached the end of its serviceable life, a full replacement may be more cost-effective than continued repairs. Transform Water carries out large-scale water tank installation for commercial and multi-residential properties across NSW, including complex multi-tank systems for high-rise and strata buildings.
Book a Commercial Tank Assessment
Transform Water works with strata managers, facility managers and commercial building owners across Sydney and regional NSW. We provide written inspection reports, clear pricing and scheduling that works around your building’s occupancy.
Book a commercial tank clean or contact us to discuss your building’s specific requirements.
Frequently Asked Questions
Are building owners legally required to clean their water tanks?
Yes. Under the Public Health Act 2010 (NSW), building owners and operators have a duty to take all reasonably practicable steps to ensure water stored on their premises is safe. Regular inspection and cleaning of water storage tanks is part of meeting this obligation.
How often does a strata building water tank need to be cleaned?
Tanks supplying potable water in strata buildings should be cleaned every 1 to 2 years. Non-potable tanks used for toilet flushing or irrigation can be cleaned every 2 to 3 years. Fire water tanks must follow the AS1851 inspection and maintenance schedule.
Who is responsible for water tank maintenance in a strata building?
The body corporate is legally responsible for maintaining common property water tanks in a strata building. This responsibility is often managed by a strata manager on their behalf, but the legal obligation remains with the body corporate or building owner.
Do commercial water tank cleaning contractors need special certification?
For tanks requiring confined-space entry (such as underground or large basement tanks), contractors must hold confined-space certification and follow applicable safe-work procedures. Always confirm your contractor’s certification before booking work on enclosed or underground tanks.
What records should a strata manager keep for water tank maintenance?
Strata managers should keep copies of all tank inspection reports, cleaning reports and any repair records as part of the building’s maintenance register. These records demonstrate compliance and are important in the event of a regulatory audit or liability claim.
