Wet Areas

Poor wet area design or installation can compromise safety, comfort and convenience for building users, and lead to significant structural damage.

Managing water overflow and splashing

Wet areas should be designed to minimise damage from water overflow and splashing.

On this page:

  • preventing overflow damage
  • preventing damage from splashing

Acceptable Solution E3/AS1 provides a means of compliance for three aspects of wet area design. Acceptable Solution E3/AS2 Internal Wet-area Membrane Systems provides a means of compliance for Building Code clauses E3.3.2E3.3.6.

Preventing overflow damage

Overflow or flooding is generally the result of user error such as leaving a tap running, a blocked outlet, a leaking pipe or joint or a faulty appliance. Flooding is often not considered during the design of a wet area but, if uncontained, water can damage adjacent rooms or occupancies. Flooding can be contained by:

  • a floor waste to drain water safely away
  • continuous, impervious floor coverings
  • coved or sealed floor-wall junctions.

Floor wastes should be installed in all:

  • upper floor wet areas
  • wet areas with a high risk of flooding, e.g. facilities for children or elderly

It is a statutory requirement to provide floor wastes or drains in multi-unit dwellings.

Other measures to minimise the risk of flooding include:

  • ensuring that the floor falls to the floor waste (this is a mandatory requirement within the shower area)
  • incorporating a water barrier at doorways to wet areas
  • specifying fixtures with inbuilt overflows
  • ensuring subtrades know where pipes are located (to reduce the likelihood of a tradesperson inadvertently damaging a pipe during construction)
  • specifying fixtures for hand washing only with spray taps and no plugs
  • specifying taps with a timer or automatic turn-off for some situations
  • fitting pressure reducing valves or flow restrictors in facilities such as accommodation for the elderly
  • specifying hose burst valves for high water use appliances such as washing machines and dishwashers.

Preventing damage from splashing

E3/AS1 requires impervious and easily cleaned finishes to floors and walls subject to water splash, within showers and around urinals. This will prevent damage from splashing.


Updated: 12 November 2020