WATER SERVICES
Water storage tanks: safe tray, overflow and inlet rules
A water storage tank brings its own set of rules: a tray to catch a leak, an overflow that discharges somewhere sensible, and an inlet arranged so the supply can never be contaminated by the tank.
The safe tray
A storage tank generally sits in a safe tray, watertight, with raised sides and a drain of the right size running to a safe, visible discharge point. The tank sits clear of the tray edge so the whole footprint is caught. The point is the same as for a hot water unit: a leak is taken away, not soaked into the building.
The overflow
The tank overflow is sized to handle the inflow, discharges to a readily visible spot within the property, and is kept clear of doors and windows so an overflow is noticed rather than hidden. An undersized or concealed overflow is a common pull-up.
The inlet and cross-connection
The supply inlet to the tank discharges above the maximum liquid level, never submerged, so water cannot be drawn back out of the tank into the supply. Where that air gap cannot be maintained, backflow prevention is required instead.
What to photograph
Show the tank in its tray, the overflow and where it discharges, and the inlet arrangement. Elemetric keeps that set with the job.
Common questions
Does a water storage tank need a safe tray?
Generally yes. The tank sits in a watertight tray with raised sides and a drain to a safe, visible point, so a leak is taken away rather than soaking into the building.
Where does the tank overflow discharge?
To a readily visible spot within the property, clear of doors and windows, and sized to handle the inflow, so an overflow is noticed rather than hidden.
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Download on the App Store →General information for licensed tradespeople, not legal or regulatory advice. The licensed plumber remains solely responsible for compliance. Refer to the current AS/NZS 3500 standards and the Building and Plumbing Commission (formerly the VBA) for authoritative requirements.