California Code, Health and Safety Code - HSC § 116780

(a) Unless the context otherwise requires the definitions in this section govern the construction of this article.

(b) “Clock control” means the system controlling the periodic automatic regeneration of a residential water softening or conditioning appliance that is based upon a predetermined and preset time schedule.

(c) “Demand control” means the system controlling the periodic automatic regeneration of a residential water softening or conditioning appliance that is based either upon a sensor that detects imminent exhaustion of the active softening or conditioning material or upon the measurement of the volume of water passing through the appliance. A demand control system activates regeneration based upon the state of the equipment and its ability to continue the softening process.

(d) “Fully manual regeneration” means the method of regeneration of a residential water softening or conditioning appliance in which operations are performed manually and in which dry salt is added directly to the ion-exchanger tank after sufficient water is removed to make room for the salt.

(e) “Hardness” means the total of all dissolved calcium, magnesium, iron and other heavy metal salts, that interact with soaps and detergents in a manner that the efficiency of soaps and detergents for cleansing purposes is impaired. Hardness is expressed in grains per gallon or milligrams per liter as if all such salts were present as calcium carbonate.

(f) “Local agency” means a city, county, city and county, district, or any other political subdivision of the state.

(g) “Manually initiated control” means the system controlling the periodic regeneration of a residential water softening or conditioning appliance in which all operations, including bypass of hard water and return to service, are performed automatically after manual initiation.

(h) “Regeneration” means the phase of operation of a water softening or conditioning appliance whereby the capability of the appliance to remove hardness from water is renewed by the application of a brine solution of sodium or potassium chloride salt to the active softening or conditioning material contained therein followed by a subsequent rinsing of the active softening or conditioning material.

(i) “Salt efficiency rating” means the efficiency of the use of sodium chloride salt in the regeneration of a water softening appliance, expressed in terms of hardness removal capacity of the appliance per pound of salt used in the regeneration process. The units of salt efficiency rating are grains of hardness removed per pound of salt used. One grain of hardness per gallon is approximately equivalent to 17.1 milligrams of hardness per liter.