Hot water risk

Domestic hot water scalding risk

The Health and Safety Executive (HSE) has issued a safety alert to individual homeowners, tenants, landlords and the plumbing industry.

This safety alert has been issued to raise awareness of a rare but potentially serious risk of scalding from domestic hot water systems, where there is a fixed, all electric or part electric immersion heater in conjunction with a plastic cold water storage cistern or tank located in the roof space.

The alert follows two similar fatal incidents in the last four years where a large quantity of near boiling water poured through bedroom ceilings onto occupants sleeping below.

This was caused by a combination of:

  • The electric thermostat failing and overheating
  • The plastic storage cistern/tank located in the roof space being inadequately supported

An overheating immersion cylinder will normally show obvious warning signs. Serious incidents like these are therefore likely to be extremely rare. However, there is a number of steps that can be taken to reduce the risk.

Occupants should be aware of warning signs indicating a possible thermostat failure. Typical warning signs include:

  • Excessively hot water coming out of the hot water taps
  • Excessive noise or 'bubbling'; from the hot water cylinder
  • Hot water coming out of certain cold water taps (some storage cisterns also feed cold water taps in the bathroom)
  • Steam/moisture in the roof space

Storage cisterns should be installed on an adequate supporting base. The incidents that prompted this alert occurred primarily because plastic storage tanks/cisterns were not supported across their entire area in other words, the base of the cistern protruded over the edge of the base support board.

A safety cut off feature, independent of the emersion heater thermostat, can be fitted.

In such circumstances the householder or tenant should switch off the immersion heater system. Tenants should alert their landlord. Householders should seek advice from a competent person such as a qualified plumber.

Last updated: 24/06/2010 14:18

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