Both companies – who must also each pay £50,000 in legal costs - had previously pleaded guilty to contravening the Health and Safety at Work Act 1974 following the incident in 2003.
At inquests the coroner directly linked the deaths of two people to the outbreak and the Health Protection Agency concluded it had caused 26 cases of Legionnaire’s disease.
Following the hearing at Hereford Crown Court the Health and Safety Executive (HSE) has urged companies to ensure water storage and cooling systems are adequately treated to prevent the growth of the legionella bacteria - which affects around 300 people in the UK each year.
Speaking after the case HSE investigating inspector Tony Woodward said: 'There was a failure to institute and maintain an effective cleansing treatment and disinfectant regime for two seasonably used cooling towers, at Bulmer's site in the Cider Mills, Plough Lane, Hereford.
“Inadequate management, by neglecting such an obvious duty of care, that can result in the health and lives of the public or employees being endangered, cannot go unpunished.
“The fines will also help to deter any repetition although this does not help the members of the public who were adversely affected and to whom our sympathies are extended.
“The fact that building users engage a specialist contractor does not mean that they have complied with the law; they must work with the contractor and ensure they are receiving the service required.
“Equally specialist contractors and sub-contractors must provide their clients with the expertise which they have been engaged for.'
HP Bulmer Limited was fined £300,000 with costs of £50,000 after pleading guilty to a breach of Section 3(1) of the Health and Safety at Work etc Act 1974.
Northwick based Nalco Ltd was simultaneously also fined £300,000 with costs of £50,000 after also pleading guilty to a breach of the same section which relates to ensuring the health and safety of non-employees are not put at risk by a company’s actions.