Do you have any documentation on this? Primary standards on drinking water do not include phosphate (nor do secondary standards, for that matter).40ppm considered safe for drinking water by epa.
https://www.epa.gov/ground-water-and-drinking-water/national-primary-drinking-water-regulationshttps://www.epa.gov/sdwa/secondary-drinking-water-standards-guidance-nuisance-chemicals