The Health Protection Agency said the latest case brings the total to 21. The patient, who is being treated at the University Hospital of North Staffordshire, is a man in his 70s.
Two patients being treated for the disease since the spate of illnesses began in the middle of July have died.
A man has been arrested on suspicion of attempted murder after explosions at three homes.
Staffordshire Police said officers received reports of blasts at houses in the Stoke-on-Trent and Staffordshire Moorlands area last night.
A spokesman said:
A 44-year-old man from Cheadle was arrested on suspicion of attempted murder and is currently being interviewed by detectives.
Eight patients are now in hospital after an outbreak of Legionnaires' disease.
Staff at the University Hospital of North Staffordshire say there are no new cases of Legionnaires' Disease to report in Stoke-on-Trent today.
The total number of cases remains at 16.
Health officials are awaiting details of the cause of death of a patient suffering from Legionnaires' disease.
No further details were released about the person who died. The patient was among 16 confirmed cases in the city of Stoke-on-Trent.
The Health Protection Agency has confirmed one of the people being treated for Legionnaires' disease in Stoke-on-Trent, Staffordshire has died.
Seven people are being treated in hospital with Legionnaires' disease in Stoke-on-Trent.
The patients range in age from their late 40s - 75 years old:
- A man in his 40s
- A woman in her 50s
- Two men in their 50s
- Three men in their 70s
Two of the three men in their seventies are said to be in a stable condition. The other patients are all recovering and improving.
There are seven confirmed cases of Legionnaire's disease in Stoke-on-Trent.
The seven patients are being treated at University Hospital of North Staffordshire.
Stoke City winger Jermaine Pennant will not face any action over claims he assaulted a woman in a nightclub at the end of April.
He was arrested after the woman complained she had been attacked in the Circle Bar in Manchester city centre.