The widely reported failure of an immersion heater thermostat on a domestic hot water system in January 2008 and the investigation and issue of a Safety Alert by the Health and Safety Executive (HSE) has lead to an Information Note being issued which relates to the technical aspects that will allow plumbers, landlords and householders to carry out the relevant system checks.
Landlords and householders are advised to check their cold water storage cistern (tank) in the roof space and to make sure it has a strong sturdy level board that supports the whole of the cistern. This should extend beyond the edges of the cistern and be properly supported underneath.
For the other checks you may need to seek professional advice. Anglian Water has a list of approved plumbers who are aware of this incident and have been issued with the all the relevant advice so should be able to help. If you are in any doubt seek professional advice.