Profile: Culligan Water Conditioning of San Antonio is an authorized distributor of water treatment equipment & supplies including water softeners, iron filters, reverse osmosis, and de-ionization equipment. Water filtration involves removing small particles like sediment, manganese, iron, chlorine, and even gases like hydrogen sulfide from the water. The filter traps these particles (in sizes as small as 10 microns), as water travels through it. Periodically the filter must be backwashed, so the unit has to be taken off-line. The flow of water through the filter is reversed, and the trapped sediment is rinsed out. When completed, the filter is ready to work again.