Shropshire Council met officials from Public Health England to discuss the hotel on Thursday and decided more work is needed.
Matthew Aldridge, health protection team manager at Shropshire Council, said: “Further works at the Feathers Hotel are still ongoing and the hotel won’t reopen until the relevant assurances have been provided.”
The hotel was closed in September and reopened after two months of remedial work.
Elaine Brown, 69, died on August 26 last year after suffering a stroke as a result of the disease, which was linked to bacteria in the plumbing at the hotel.
Another guest contracted the disease and was diagnosed in April 2017.
They have since recovered from the disease.
Legionella organisms are commonly found within water in the natural environment.
When levels of the bacteria are elevated in water supply systems there may be a risk of contracting Legionnaires’ disease within 14 days of exposure.
The Feathers was put up for sale in January for more than £2.6 million.
The hotel was built in 1619 and is one of Ludlow’s best-known listed buildings.
Earlier this year, a joint statement from both the council and PHE confirmed the measures taken to prevent any further incidents.
It said: “Following routine sampling of the water system at the Feathers Hotel by Shropshire Council’s regulatory services team, elevated levels of Legionella have been detected in the water system at the hotel.
“Working with Public Health England, a joint decision has been made to implement urgent measures to reduce Legionella levels in the water system and prevent any risk to staff and guests who use the hotel.
“This includes a temporary voluntary closure of parts of the hotel until further precautionary works can be carried out.”