Rated Capacity - the basis for calculating the period of time, or number of gallons delivered by a water softener or filter, between regenerations or servicing, as determined under specific test conditions.
Rated Pressure Drop - the pressure drop of water softener or filter at the rated service flow, with clean water at a temperature of 60degrees. with a freshly regenerated and/or backwashed softener or filter, as determined under standard test conditions.
Rated Service Flow - the manufacturer's specified maximum flow rate at which a water softener will deliver soft water, or a filter will deliver quality water as specified for its type, as determined under standard test conditions. A manufacturer may also specify a minimum flow rate or a range of service flows.
Rated Softener Capacity - a water softener capacity rating based on grains of hardness re-moved while producing soft water between successive regenerations, as determined under standard test conditions.
Raw Water - untreated water, or any water before it reaches a specific water treatment device or process.
Red Water - water which has a reddish or brownish appearance due to the presence of precipitated iron and/or iron bacteria.
Reduction - a chemical process in which electrons are added to an atom, ion or compound.
Regenerant - a solution of a chemical compound used to restore the capacity of an ion exchange system. Sodium chloride brine is used as a regenerant for ion exchange water softeners, and acids and bases are used as regenerants for the cation and anion resins used in demineralization.
Regeneration - in general, includes the backwash, brine, and fresh water rinse steps, necessary to prepare a water softener exchange bed for service after exhaustion. Specifically, the term may be applied to the 'brine' step in which the sodium chloride solution is passed through the exchanger bed. The term may also be used for similar operations relating to the demineralizers and certain filters.
Regeneration Level - the quantity of regenerant used in the regeneration of an ion exchange unit , usually expressed in pounds per regeneration and/or pounds per regeneration per cubic foot of ion exchange.
Residual - the amount of a specific material remaining in the water following a water treatment process. May refer to material remaining as a result of incomplete removal or to material meant to remain in the treated water.
Resin - synthetic organic ion exchange material, such as the high capacity exchange resin widely used in water softeners.
Reverse Deionization - the use of the anion exchange resin ahead of the cation exchange resin in a deionization system.
Reverse Osmosis - a process for the removal of dissolved ions from water, in which pressure is used to force the water through semipermeable membrane, which will transmit the water but reject most other dissolved materials.