... purifier1. The first stage is 5.0 micron PP filter .filtering s, rust, mud, sediment, etc. in water.2. The second ... stage is Milfunction+active carbon removing bad smell filtering organic sediment in water.3. The third stage is USA ... water.4. The fourth stage is 400G Reverse osmosis membrane filtering germ, virus, corpuscule, other solute chemical from tap water processing ...