A former Health and Safety Executive (HSE) adviser said he is “deeply concerned” that legionella bacteria at Sutton Hospital could be more widespread.

Councillor Stuart Gordon-Bullock, now chairman of the Sutton Council health scrutiny committee, is seeking reassurances from St Helier Hospital.

In a letter to Peter Coles, acting chief executive of Epsom and St Helier NHS Trust, he has asked for the findings of water tests at the site to be made public.

Coun Bullock wrote: “From my experience with the HSE this is an eminently easy problem to deal with and I must express concern that safe systems of work and maintenance of pipework had not dealt with the problem on the Sutton Hospital site.

"This raises questions about how safe the water systems are on the rest of the Sutton and St Helier sites, as both sites are under your control.”

“I would be grateful for details of what systems of work you have for the control of this biological hazard – in particular, are there any wet cooling towers on the St Helier site; and what the latest test results are for water in the systems at St Helier and the rest of the Sutton site.”

The trust said independent specialists conducted rigorous water tests at its three hospital sites.

A spokesman said: “These stringent tests are essential to ensure the trust meets all necessary standards to comply with its obligations to provide safe water services in healthcare premises.

“As a precautionary measure, we have recently undertaken further water sample tests at Sutton Hospital.

"These are purely a preventive measure, to monitor any changes to the water services provided.

“The trust has invested more than £1m over three years on improving the standards of its water supplies.”