First, phosphate isn't a disinfectant. It is a substance that helps to soften water. The bonds between water molecules come undone and that enables the water to act as a solvent and to clean things. So it's not an element that disinfects, like chlorine or ozone. A little earlier, I was looking at the calculations in your study. It states that every resident produced about 80 grams of phosphates in water and that approximately 50% of that phosphate came from personal items, from the home.
On June 4th, 2008. See this statement in context.