Using orthophosphate for the interior coating of lead water services?

We, (Water Dept), currently add orthophosphate to control lead levels in our drinking water supply as a corrosion treatment and lead levels have been significantly reduced. However, customers have complained about the smell and/or taste of the drinking water. My question is if there are any health risks to our using orthophosphate in such a manner, especially to chemically sensitive individuals? More of our customers have been purchasing bottled water for drinking instead of our tap water because of suspicion that our water is causing stomach problems and I would really like to know of any connection of illness linked to orthophosphate in drinking water?

I am very interested to the answer of this question. We have had an area wide aggressive water problem in our town and would like to know if increasing orthophosphate to the public water supply is a health risk. We are also considering in home orthophosphate treatments to remediate the copper corrosion problems. Thanks.