ok a few questions for you
how old is your house / plumbing ?
do you know what your pipes are made of ?
can u do a tap water test and leave it in a clear container for 24>36 hours ?
only reason i ask is because i recently had to deal with a similar problem with a tank i was setting up for a family member,
i set the tank up and go home for the night get a call the next morning saying the tank was blue ended up being due to
'blue water' a condition due to corroding copper pipes in melbourne.
for those interested