Officials believe the Legionnaires outbreak at Stoke On Trent can be traced to a hot tub in a Stoke warehouse.
The Staffordshire Cluster of Primary Care Trusts say a hot tub display at the JTF Mega discount store in Fenton, Stoke On Trent is the probable source of the disease.
One patient has died in hospital whilst being treated for Legionnaires though a cause of death has yet to be revealed. 18 people have been infected.
The Health Protection Agency say 17 of the 18 confirmed cases visited the warehouse in the two weeks before they fell ill.
A spokesman from the Health and Safety executive said:
"We know that spa pools are known to be effective mechanisms for spreading legionella infection.
"We may still expect to see new cases of Legionnaires' Disease related to this outbreak."
Despite JTF being named as the probable source of the outbreak, investigations continue.