In the production of bottled mineral water, the water passes through a reverse osmosis water processor to remove pollutants and microorganisms. Membrane pore sizes can vary from 0.1 to 5,000 nm (4×10−9 to 2×10−4 in) depending on filter type. Particle filtration removes particles of 1 μm (3.9×10−5 in) or larger. Microfiltration removes particles of 50 nm or larger. Ultrafiltration removes particles of roughly 3 nm or larger. Nanofiltration removes particles of 1 nm or larger. Reverse osmosis is in the final category of membrane filtration, hyperfiltration, and removes particles larger than 0.1 nm.