I did not try and scale sterile over "pure". And iron is one of the baddest components of all dissolved solids. Pnichols, you are aware of what you have, and that is the main point. The lab test IMHO is just good uncommon sense.
Sterilizing water is an art-form. The most thorough sterilization is not filtration even RO. Ozone treatment then sealed containment of ozonated water immediately after O3 treatment produces water that stays sterile for a year.
Reverse Osmosis has taken on buzzword status. RO processed water can range from darned near mineral free to 100 ppm. Pure water demands ultra fine filtration. ultra fine filtration demands special membrane RO components. It takes a lot of pressure to produce low TDS water. Ten times that of normal water pressure. A high pressure pump is used and membranes cost considerably more than undersink tinker toy grade RO membranes. A membrane that can withstand deterioration from the effects of sodium hypochorite is not a true high grade RO filter.
A TDS meter reveals the amount of minerals in water. Use a lab test to detect pathogens, carcinogens, and toxic pollution. Meeanwhile, tomorrow, I get to supervise the repair of a Kenmineralized washing machine (packed with deposits). Ever see an empty 130 pound 20 gallon electric water heater? That was in July. A communal water softener is in the planning stages.
But then again, for some, ignorance is bliss...