It isn't just drinking it that can cause problems, here is a recent post of mine on the PBO forum:
When did you last disinfect your shower head
As some of you may know, I've been in hospital with pneumonia. Soon after being released my CRP blood test had climbed back to 85: normal is under 10 (on admittance to hospital it was over 300, down to 25 when they released me).
Ten years ago my wife and I were both infected by Legionella in a spa hotel
. Because they had overbooked, on the first night they put us in a rarely used room, at the time I was sure this is where the infection occurred, from the shower
After trying six other types, I am now on a more powerful antibiotic (Ciproxin) which is one that is used for Legionella (and Antrax). I seem to be getting better, it is possible that this was Legionella again.
I became unwell two weeks after arriving on my boat, the first visit for several months. We arrived late at night, I wanted a shower, and I had removed the light fitting on the previous trip. I didn't disinfect the shower head. I would normally do this by removing it, putting it in the basin with some citric acid to descale it, then rinse and soak in a bleach solution. When the calorifier
has heated up, fit the shower head to the hose, hold the head under the bleach water (to avoid generating spray droplets), and turn the shower on at the maximum temperature.
This could all be a coincidence, but I urge you to read up on this subject, here is the HSE guideline.
Read more at Disinfecting Shower Heads