flux, solider, pipe dope, dead bugs, dirt,
what ever was in the pipes from the trucking company to the warehouse mice.
just run the water for a couple of hours it will be fine.
hook a hose up out side and let it run.
your water will be cloudy for a couple of days, it will be fine.
if it really gets to bugging you and you just cant leave good enough alone.
turn off the water, drain your pipes. inject half a gallon of clorox into your pipes. turn on the water
DO NOT OPEN any faucets. let it sit over night. then...remove all strainers..
then flush your system a minimum 2 hours, EVERY outlet
this is how comercial buildings are sanitised as per health department regulations