What to Do with Your Flood-Affected Hot Water System:

A Comprehensive Guide for Brisbane 2022

flooded hot water systems Brisbane


Following the significant flooding event which has occurred in Brisbane, Conrad Martens Plumbing & Hot Water has compiled a guide for dealing with hot water units that have been submerged or partially submerged in floodwaters.

This information is based on advice from the major hot water manufacturers such as Rheem, Vulcan, Aquamax, Dux and Rinnai and is designed to provide general guidance. A professional hot water specialist should assess individual installations to ensure the safe and correct operation of the system.

The general guidance from hot water manufacturers is that in most cases, systems affected by flood water will need to be replaced. The impact of water can vary depending on the style of the water heater and the severity of the flood. According to Rinnai’s press release in response to the 2022 floods in QLD, “as a general rule submerged water heaters will have:

  • Electrical components such as fan motors, pumps, electromechanical controls and printed circuit boards may be damaged beyond repair. Even if they are still operational, their safety and functionality cannot be guaranteed and their life is likely to be very limited.
  • In the case of gas appliances, silt can lodge under the seats of the gas valves, injectors and burners and lodge in the operational mechanisms of modulating gas control valves. These may lead to poor combustion and unreliable operation. At worst, these may prevent 100% shut off of the gas supply, which may lead to gas leaks or explosive ignition.
  • Other components of the water heater such as insulation may be rendered ineffective, thereby affecting the operation of the water heater.

If contaminated water has entered a water heater, the quality of the potable water provided may be compromised and it is recommended that the unit be replaced. “

It may be possible, in some instances, to salvage a flooded hot water unit. Depending on the type of water heater, repair may or may not be economically viable. When considering these options, it is important to consider the age of the water heater and the manufactures minimum requirements of those repairs.

Example 1: A 2-year-old five-star gas storage hot water system (i.e. A Rheem Stellar 330 or Dux Prodigy 5) is submerged with water. Unfortunately, due to the design of these units, replacement is always required. The manufacturer guidelines state that repair or operation of a 5 Star gas heater should not be attempted if the unit has been partially submerged.

Example 2: A Rheem electric hot water unit less than 5 years old that has been partially submerged by flood water may be suitable for repair. This would involve:

  • Cleaning and drying the terminal block and wiring
  • Carrying out a resistance test on the element and replacing if it fails.
  • Replacing the thermostat.
  • Testing the TP&R valve and replacing if required.

Example 3: A Saxon heat exchange water heater is ten years old and has been partially submerged. Due to the age of the system and the cost of replacement parts, the repair is not economical. We would recommend replacement with a standard electric unit.

Manufactures warnings and recommendations:

  • All service, repair and replacement work on a hot water system MUST be carried out by licensed, qualified, skilled and competent persons.
  • Any hot water system with an electrical connection must be isolated prior to carried out immediately.
  • Any hot water system connected to a gas supply should be isolated as soon as possible.


My Hot Water system has flooded. What is the first thing I should do?

If your hot water system has been flooded, your first consideration should be safety.
Electrical Hot Water Unit – Turn off the Power at the switchboard. Do not attempt to remove the electrical cover. Isolate the water supply to the unit if possible. Call a licenced Hot Water Specialist.

Panel switch connected to the electrical hot water unit.

Gas Storage Water Heater – Turn off the Gas Supply at the isolation valve. This valve will often have a yellow handle and be positioned towards the base of the tank. Also, turn off the water supply if possible.
continuous flow
Continuous Flow (instantaneous) – Isolate the unit’s power, gas, and water supply. These valves should be positioned below the hot water unit.
solar and heat pump
Solar and Heat Pump – Turn off the Power at the switchboard. Do not attempt to remove the electrical cover.


Several factors influence if a flooded hot water unit can be economically repaired or should be replaced.
Depending on the severity of the flood and the model and age of your hot water unit, it may be possible to repair your flooded water heater.


If you have been affected by floodwater, we recommend contacting Home and Contents Insurance provider to discuss your situation and review your policy. Your cover may include loss or damage to your property and contents affected by the flood.
When arranging restoration work, it is essential to remember that the account holder, not the insurer, is responsible for the payment of the account.

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