This pertains more to the linked thread, but may be relevant to those with copper, or lead pipes.
A little over 10 years ago, many public water suppliers started adding a tiny amount of phosphate (as mandated by the EPA) to the distribution systems, to coat the inside of pipes , and prevent the leaching of lead and copper into homes.(most lead and copper are " Not" in the distribution system itself, but in the private homes plumbing)
The facility I worked at, did this addition of phosphate, and as a chemist at the plant I was involved in the research to see how much, and if, the addition of phosphate actually helped reduce leaching.
My house went from a lead and copper concentration of about 12ppb (parts per billion (under the MCL of 15ppb)) to less than 5 ppm after a few months into the study of phosphate addition.
I found this rather encouraging