When is a Pressure Limiting Valve (PLV) required?
Summary (TL;DR)
Under AS/NZS 3500.1, a Pressure Limiting Valve (PLV) must be installed if the static water pressure at any outlet within a building exceeds 500 kPa. The PLV is typically installed at the property boundary or on the main supply line before it branches to fixtures.
Pressure Limiting Valve (PLV) Rules
High water pressure is the leading cause of burst flexi-hoses, leaking tapware, and blown hot water relief valves. AS/NZS 3500.1 mandates pressure control to protect the plumbing system and the building.
The 500 kPa Maximum
The standard strictly states that the maximum static pressure at any outlet within a building (other than a fire service outlet) shall not exceed 500 kPa (50 metres head).
Where to Install the PLV
If the mains pressure from the street exceeds 500 kPa, you must install a PLV. It should ideally be installed:
- At the property boundary, immediately downstream of the water meter and isolation valve.
- Or, on the main supply pipe before it branches off to supply any fixtures within the building.
Exceptions
Garden taps (hose bibs) located outside the building are generally exempt from the 500 kPa limit, meaning you can branch off the main line before the PLV to provide high pressure for garden hoses, provided the pipes are rated for the mains pressure.
Quote Upgrades with Confidence
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