I maintain a corporate jet and only fill the 20 gallon tanks when i know where the water in the truck came from. Yet each 6 months the water filters need replacing as they start to show signs of the black goo. We never use the water for drinking just washing hands dishes and the squirt that goes around the vac loo.
My advice is dont go near potable water even on a reputable airline because last week the water may have been filled up in somewhere you wouldnt even go let alone drink the water.