Reverse Osmosis filters feature 4-stage filtration: a sediment filter to rid your water of impurities like rust, deposits, particles, moss, and sand, a pre-carbon filter to remove heavy metals, odors, chlorine, and VOCs, a reverse osmosis filter to shed your water of lead, chromium, fluoride, and microbes, and finally a mineralizer to add electrolytes, natural calcium and potassium back to your water for healthy and pH balanced alkaline drinking water. Our Nano Positive filters feature 3-stage filtration: a pre-carbon filter to remove heavy metals, odors, chlorine, and VOCs, a mineralizer to add electrolytes, natural calcium and potassium to your water, and finally a Nano+ filter to remove heavy metals, viruses, and bacteria.