The 5-stage filter transforms your tap water into delicious, TDS-free drinking water. Get more out of your water with ZeroWater's 5-stage water filtration. 5-stage filtration stage 1 - removes suspended solids such as dust and rust that make your water appear cloudy. Stage 2 - removes additional suspended solids. Stage 4 - removes inorganic compounds ie. Metals, nonmetals and radiological contaminants. Stage 5 - removes remaining suspended solids, holds the resin in place.