The outbreak began in July and has since killed six patients in Quebec City.
Authorities say the bacteria grow in the stagnant water often found in cooling towers of ventilation systems and infect people once they're inhaled.
To date, public health inspectors have checked and disinfected 89 cooling towers in Quebec's Lower Town.
"The towers that were problematic will be revisited on Monday and Tuesday to treat them again, to have continuity for adequate disinfections," said regional director of public health, Dr. François Desbiens.
Desbiens said cooling towers outside the current perimeter would also be cleaned.
On Friday, public health authorities confirmed 16 new cases of Legionnaires' disease.
Quebec City Mayor Régis Labeaume blamed the provincial government for failing to fully implement the recommendations in a 1997 report — after the last major outbreak of Legionnaire's disease in the province.
Health minister Yves Bolduc has said the government will create a registry of buildings with cooling towers, and it will also put in place tougher regulations for inspections and maintenance of those buildings.
Asked once again Saturday why the 1997 report had not been fully implemented, Bolduc blamed the Parti Québécois, as the report was released while the PQ was in power.