A acidity a characteristic that can make water corrosive and unpleasant; acidity must generally be corrected with neutralization activated carbon carbon which has been chemically treated to improve its adsorption properties and filtration capacity adsorption the process by which contaminants react with activated carbon and are removed from water aeration an oxidation process in which air is injected into water generally to convert an unwanted substance into a solid form that can be filtered B brine the solution a water softener uses to clean its media bed of captured calcium and magnesium in preparation for service brine drum the brine preparation and holding tank on a water softener C calcite the media used in a neutralization system to neutralize acidic water carbon filtration a common water filtration method which uses activated carbon to adsorb contaminants chlorine a common water disinfectant used by municipal water utilities conditioned water water free of dissolved calcium and magnesium (hardness minerals); also referred to as soft water countercurrent regeneration  a type of regeneration in which the flow through a water conditioner is reversed during the cleaning process for greater effectiveness and efficiency cryptosporidium probably the most common and certainly the most notorious of a group of microorganisms called cysts; "crypto" was responsible for a major waterborne illness outbreak in Milwaukee in 1993 cysts any of a group of microorganisms that include entamoeba, giardia and cryptosporidium; when ingested, cysts can cause gastrointestinal illness among others and often have more problematic effects on children, the elderly and people with immune deficiencies D demand-initiated regeneration (DIR)  a process in which regeneration is initiated based upon a householdÂs water use instead of at a preset interval drinking water the one percent of a household's entire water use that is designated for drinking or food preparation; also referred to as food grade water F ferric iron  dissolved iron which has been oxidized and transformed into an orange particulate ferrous iron  dissolved clear iron; often found in well water H hard water water that contains dissolved calcium and magnesium hardness the amount of dissolved calcium and magnesium in a water sample, typically measured in grains per gallon (gpg) hydrogen sulfide an obnoxious gas with a "rotten egg" odor found in some water I ion exchange a water softening process in which hardness ions (calcium and magnesium) are exchanged for sodium or potassium ions iron a common element that is absorbed by water as it passes through the ground; iron is often found in well water and can cause rusty orange stains on clothing and household fixtures L lead a tasteless, odorless water contaminant that may be leached from lead-based solder used to join pipes M manganese iron's close cousin commonly found in well water; manganese can cause black stains on clothing and household fixtures N neutralization the process by which water's acidity is adjusted to a neutral range; acidic water can be corrosive O oxidation a process in which an oxidizer (commonly air or chlorine) reacts with a dissolved substance to convert it into a solid form that can be filtered R recovery rate a measure of a reverse osmosis system's efficiency; generally measured as amount of water produced divided by amount of water used; a rate of 25% is usually considered efficient regeneration a water conditioner's cleaning cycle; the cycle prepares the system's resin bed so it can soften water again resin tiny beads used by a water conditioner to soften water; the place where ion exchange occurs inside a water conditioner reverse osmosis a filtration method in which water is forced through a semi permeable membrane which rejects contaminants S scale a hard, crusty substance that remains after hard water dries soap scum the substance which results from the reaction of the hardness minerals in water with common household soaps; usually evident as a bathtub ring or glass shower door film soft water water free of dissolved calcium and magnesium (hardness minerals); also referred to as conditioned water solder a substance used to join pipes; lead-based solder was outlawed in the late 1980s source water untreated water that is supplied to a home or business; source water is usually best for outdoor applications like watering lawns T turbidity water cloudiness caused by suspended particles V volatile organic compounds  organic contaminants including commercial chemicals and pesticides; commonly referred to as VOC's W working water the water used in a home for most general purposes including bathing and laundering