Here are are the comon types of testing in the potable water treatment industry:   Phosphate testing for reversion Corrosion coupon testing Passivation of Lead Copper Red water filter test       In addition to phosphate testing water quality tests include “red” water filter tests and corrosion coupon testing. Corrosion coupon testing should incorporate a stagnate loop for the lead and copper passivation studies. A Lead and copper passivation study indicates the time it will take to re-passivate lead and copper after a  system up set. The shorter the time required for re passivation the more assured of passing the 90th percentile.