Adding a lead inhibitor (orthophosphate) has no negative effects on health. It is commonly used by water utilities across North America and the United Kingdom to prevent lead from entering into drinking water. Phosphate is naturally present in food and is a common additive to beverages. In fact, you would have to drink 104 glasses of tap water to match the phosphorus in one banana.
Customers undergoing dialysis or who have other kidney concerns can be impacted by phosphorous levels. You may wish to contact your doctor to discuss the orthophosphate addition and if it will have an affect on any health concerns.
Lead is harmful to health, especially in children and pregnant women. Adding orthophosphate to water treatment is an important step to mitigate other health problems from exposure to lead.