ZeroWater® Tumbler Replacement Filters, 2-pack. ZeroWater's5-stage filtration technology removes 2x the TDS * versus leading competitors. The * ?Color Change? window indicates when it is time to replace your filter. The 5-stage filter transforms 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 3 - Removes organic contaminants; pesticides, herbicides, Mercury, Chlorine, Chloramine and stops bacteria from growing. Stage 4 - Removes inorganic compounds i.e. metals, nonmetals and radiological contaminants. Stage 5 - Removes remaining suspended solids, holds the resin in place.