Maintenance of hot tubs?

What is the best procedure for preventing Legionella becoming a problem in my hot tub? I currently use chlorine as a disinfectant but I am concerned that sometimes this runs out and I understand that the bacteria can build up in the air injector lines. Also if there is chlorine in the water and Legionella builds up in the air lines is the Legionella killed off when the air is turned on when it passes through the chlorinated water?

Legionella must be in contact with the active biocide (chlorine, bromine, etc.) for a sufficient amount of time and at a concentration of the biocide that is active against Legionella. So, control of Legionella would occur in the liquid phase. Maintain the biocide concentration at the recommended level, monitor your biocide levels and keep the system clean. This should keep your system under control.

We also believe some of the outbreaks attributed to hot tubs were incorrect and the drinking water was the actual source.