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Important

New version effective 20 April 2026

This is the new version of the licensing criterion and associated guidance.

Criterion HS110#

# Water stored in any hot water cylinder is kept at a temperature of at least 60°C. Any malfunctioning hot water cylinder is inspected and repaired as necessary.

Guidance #

How to show you are complying #

If you use a hot water cylinder, the cylinder’s thermostat must be set at 60°C or higher. 

Inspecting and repairing malfunctioning hot water cylinders#

You must use a licensed plumber or gasfitter to inspect and repair a hot water cylinder when necessary. 

We would expect you to engage a licensed plumber or gasfitter if:

  • the thermostat is set at the correct level, but the water is cold or lukewarm
  • hot water runs out quickly
  • the hot water cylinder is making unusual sounds – this may indicate sediment buildup at the bottom of the tank
  • the base of the cylinder is damp, or water is pooling in that area – this could indicate there a leak or a pressure issue
  • there is brown or rusty water emanating from hot water taps – this may indicate internal corrosion or a failing anode rod
  • there is a noticeable drop in pressure from hot water taps – this could be due to sediment clogging pipes or valves
  • there is a sudden and unexplainable increase in electricity usage – this might mean the cylinder is working inefficiently or constantly reheating
  • the water from hot water taps is too hot or not hot enough – this may indicate the thermostat or heating element may be faulty
  • there are signs of rust or corrosion on the hot water cylinder or fittings – this can be a sign that it is aging and may stop working in the future.