You guys should worry more about what might be living in your fuel tanks.
Having been slagged off as an unwelcome grease monkey elsewhere in these hallowed forums I hesitate to interfe, but maintenance do carry out routine hyperchlorination and yes, surprise, surprise - it does leave a taste in the water. The water is uplifted into the water bowser from a certified source that is regularly checked by the local authority. The hose system is a sealed coupling - what's outside has no bearing on what's inside the hoses. A certain amount of slime and those "waving fronds" sloshing about are an indication of a healthy water environment - ask my goldfish, they should know and three of them are ten years old.
The water in your aeroplane is as clean as the water in the office. Take a wander up to the roof one day and have shufti inside the water tank there...
