Hardness - A water quality parameter that indicates the level of alkaline salts, principally calcium, magnesium, and iron, and expressed as equivalent calcium carbonate (CaCO3). Hard water is commonly recognized by the increased quantities of soap, detergent or shampoo necessary to raise a lather.
Hydraulic gradient - see gradient, hydraulic.
In-lieu recharge - A term used by ADWR to describe the process of using a renewable supply instead of pumping groundwater at a Groundwater Savings Facility. No water is actually recharged.
Impact fee - A fee charged to developers to cover part or all of the costs of providing services, such as sewers, water connections, and roads. Such a fee is allowed but not required under state law.
Incidental recharge - Water incidentally added to a groundwater aquifer due to human activities, such as excess irrigation water applied to fields or water discharged as waste after a use. See also recharge, artificial recharge, natural recharge.
Infiltration - The process of water entering the soil or streambed surface.
Injection well - An artificial structure (usually an existing well) used to recharge the water table by forcing water down the well.
Irrigation district - A political entity created to secure and distribute water supplies. Most irrigation districts provide water for irrigation on farms, but some which originated for agricultural purposes now primarily serve municipal customers.
mg/l - Milligrams per liter - Roughly equivalent to parts per million (see below).
Microfiltration (uf) - a form of filtration using a membrane with larger pores than nanofiltration. It is highly effective in removing pathogens, including parasites such as giardia, but does not remove salts. Because it has large pores, UF does not leave a saline concentrate, although filters must be backwashed to keep the pores open.
Mineral content - See Total dissolved solids.
Mountain front recharge - Natural recharge that occurs at the base of the mountains because of rainfall or snow melt at higher elevations.
Municipal water use - All non-irrigation uses of water supplied by a city, town, private water company or irrigation district. Generally includes domestic, commercial, public and some industrial uses.
Nanofiltration (NF) - A form of filtration using membranes with larger pores than reverse osmosis. NF removes most salts, pathogens and organics. Like RO the process requires pretreatment of water with chemicals or a sand-based system. NF has not been used commercially on a large scale for drinking water.
Natural recharge - Natural replenishment of an aquifer generally from snowmelt and storm runoff. See also recharge, artificial recharge, incidental recharge.
Ozone - A highly reactive form of oxygen (O3) used to disinfect water.
Non-consumptive use - A water use that leaves the water available for other potential uses, usually after it has been collected in a sewage system. Most indoor uses are largely non-consumptive. Compare with consumptive use.
Parts per million (ppm) and parts per billion (ppb) - A measures of the concentration of materials in a liquid, often used to describe the degree of contamination of water. One ppm indicates that for each one millions units of water there is one unit of the contaminant, One ppb indicates that for each one billion units of water there is one unit of the contaminant. 1 ppm is approximately equal to 1 mg/L.
Permeability - A measure of the relative ease with which a porous medium can transmit a liquid under a potential gradient.
pH - A measure of the relative acidity of water. Below 7 is increasingly acid, 7 is neutral and above 7 is increasingly alkaline.
Potable water - Water that is suitable for drinking, from a Latin word meaning “drink.”
Primary treatment - Initial treatment given to sewage, usually removal of solids and possibly some disinfection.
Private water utility - A water provider that is owned by individuals or a corporation and sells water to customers.
Protozoa - Microscopic animals that occur as single cells. Some can cause disease in humans. They are not destroyed by disinfection, but can be destroyed by filtration.
Public utility - A water or power provider owned by a government such as a city or town.
Recharge - Augmentation of the groundwater by the addition of water. See natural recharge, artificial recharge, incidental recharge.
Reclaimed water - Tertiary-treated water available for use on turf or other facilities.
Reservoir - A facility for storing water until it is to be used. A reservoir may be open or covered.
Reverse osmosis - A process whereby water is forced through membranes that contain holes so small that even salts cannot pass through them. It removes microorganisms, organic chemicals and inorganic chemicals, producing very pure water.
Runoff - Drainage or flood discharge which leaves an area as surface flow or as pipeline flow, having reached a channel or pipeline by either surface or sub-surface routes.
Safe yield - A groundwater management goal which attempts to achieve and thereafter maintain a long-term balance between the annual amount of groundwater withdrawn in an Active Management Area and the annual amount of natural and artificial recharge within a designated area.
Secondary treatment - The most common level of treatment of sewage, involving removal of solids, use of bacterial action for purification, and the addition of disinfectants.
Service area - The area served by a municipal water provider, within which it may hold a monopoly.
Sewage - Water that has been used by individuals or businesses and needs treatment.
Sewer - A pipeline used to transport sewage to a treatment facility.
Sludge - Solids left over from the wastewater treatment process.
Sodium - A mineral which occurs naturally in most water.
Soft water - Water with relatively low concentrations of certain dissolved minerals, principally calcium, magnesium, and iron. Water from which these minerals have been mostly removed, usually through an ion exchange process.
Soil-aquifer treatment - A method of treating water by letting it seep through soil and other materials to mitigate pollution.
Subsidence - Downward movement of the land surface associated with groundwater pumping, especially where such pumping exceeds safe yield and the water table has dropped. Uneven rates of subsidence over an area can lead to differential subsidence, which can cause lateral movement of the land surface, and cracks and fissures to appear. This is more likely to occur in areas where the aquifer varies in thickness, such as near the edges of groundwater basins. Subsidence is an essentially irreversible process, not greatly ameliorated by later raising the water table.
Subsurface water - All water below the land surface, including soil moisture, capillary fringe water in the vadose zone, and groundwater.