Delivery driver Allan Bruce, 39, woke up face down on the floor with his smoke-alarm ringing after he lost consciousness while making toast.
He had put his symptoms down to a summer bug - the symptoms of Legionnaires' are similar to flu.
However, he was rushed to Glasgow's Western Infirmary after his temperature soared to a life-threatening 41 degrees and he became too weak to walk.
Allan, who was the 10th person to contract the disease, has accused Renfrewshire Council and NHS Greater Glasgow and Clyde of "playing down" the seriousness of the illness. He spent almost two weeks in hospital, lost two-and-half-stones in weight and has now developed liver problems.
Doctors believe Allan, from Dalmuir, in Clydebank, may have may become infected while making deliveries in the Renfrew area, with his windows open in the July heat.
The council is still investigating the cause of the outbreak which has affected 11 people so far. A new case was discovered last week and is still being treated in hospital.
All active water-cooling towers in the area have been treated and samples are currently being tested.
Allan said: "All the statements from the health board and council always say that patients have recovered but being discharged from hospital is only the beginning of your recovery.
"It really is a horrendous disease. I would hate to imagine someone elderly getting this. I'm looking at two months off work."
Allan was rushed to hospital on June 28 after he made an emergency appointment at his local health centre. He was struggling to walk and medics realised the seriousness of his condition.
Hospital doctors initially did not know what had caused Allan's symptoms as he lay for days in intensive care, drifting in and out of consciousness. He was tested for Legionnaires' disease after they discovered he had made deliveries in the Renfrew area.
He was later transferred to the infectious diseases unit at Gartnavel and treated successfully.
He said: "I had been feeling really unwell for a couple of weeks before but just put it down to a flu.
"I was feeling really weak and had sickness and diarrhoea. I couldn't keep anything down.
"On June 28 I was making myself a bit of toast. I went to sit down and woke up in the hall face down. I made an emergency appointment with my local health centre, and by 4pm I was in the Western.
I REMEMBER getting a lot of IV drugs. They told me the infection was very serious.
"Once I started coming round, they asked me if I had been in the Renfrew area.
"I'm a bit of a key to the infection because I've only driven there a few times so it might help them pinpoint the source. They asked for the tracker system on my truck.
"I've lost two-and-half stones in five weeks. I'm trying to build myself up now, but I still feel weak and I have pins and needles in my arms and legs.
"I've also developed a problem with my liver."
Patients, like Allan, may be entitled to compensation if the source of the outbreak is identified and anyone is found to be at fault. Other cases in the UK have won five-figure sum of money.
However, experts say that while Legionella is simple to diagnose in a person because of the body's response, it is much more difficult to detect in water samples in a lab.
HEALTH officials in Edinburgh are still working to find the source of an outbreak which killed four people and affected 45 last year.
Allan said: "Everything is very hush-hush. I know they have treated all the water coolers but they seem to be still oblivious to the source. I feel frustrated that you can become so seriously ill, just going to work."