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Water glossary



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Water Glossary - P

  • Parameter: A variable, measurable property whose value is a determinant of the characteristics of a system such as water. Temperature, pressure, and density are examples of parameters.

  • Partial pressure: That pressure of a gas in a liquid, which is in equilibrium with the solution. In a mixture of gases, the partial pressure of any one gas is the total pressure times the fraction of the gas in the mixture (by volume or number of molecules).

  • Particle size: The sizes of a particle, determined by the smallest dimension, for instance a diameter. It is usually expressed in micron measurements.

  • Particulate loading: The mass of particulates per unit volume of water.

  • Parts per billion (ppb): Expressed as ppb; a unit of concentration equivalent to the g/l.

  • Parts per million (ppm): The number of "parts" by weight of a substance per million parts of water. This unit is commonly used to represent pollutant concentrations. Large concentrations are expressed in percentages.

  • Pasteurization: The elimination of microorganisms by heat applies for a certain period of time.

  • Pathogen: Microorganisms which can cause disease.

  • Pathogenic microorganisms: Microorganisms that can cause disease in other organisms or in humans, animals, and plants.

  • Pathogens: Disease-producing microorganisms.

  • Peak flow: In a wastewater treatment plant, the highest flow expected to be encoutered under any operational conditions, including periods of high rainfall and prolonged periods of wet weather.

  • Peak/off-peak rates: Rates charged in accordance with the most and least popular hours of water use during the day.

  • Per capita use: The average amount of water used per person during a standard time period, generally per day.

  • Percent saturation: The amount of a substance that is dissolved in a solution compared to the amount that could be dissolved in it.

  • Perched water table: Groundwater standing unprotected over a confined zone.

  • Percolating waters: Waters passing through the ground beneath the Earth's surface without a definite channel.

  • Percolation: The movement of water through the subsurface soil layers, usually continuing downward to the groundwater or water table reservoirs.

  • Perennial stream: One that flows all year round. Compare intermittent stream.

  • Perfected water right: A water right which indicates that the uses anticipated by an applicant, and made under permit, were made for beneficial use. Usually it is irrevocable unless voluntarily canceled or forfeited due to several consecutive years of nonuse.

  • Permafrost: Perennially frozen layer in the soil, found in alpine, arctic, and antarctic regions.

  • Permeability: The ability of a water bearing material to transmit water. It is measured by the quantity of water passing through a unit cross section, in a unit time, under 100 percent hydraulic gradient.

  • Persistence: Refers to the length of time a compound stays in the environment, once introduced.

  • Pesticide: A substance or mixture of substances intended for preventing, destroying, repelling, or mitigating any pest. Also, any substance or mixture of substances intended to regulate plant or leaf growth. Pesticides can accumulate in the food chain and/or contaminate the environment if misused.

  • pH: Numeric value that describes the intensity of the acid or basic (alkaline) conditions of a solution. The ph scale is from 0 to 14, with the neutral point at 7.0. Values lower than 7 indicate the presence of acids and greater than 7.0 the presence of alkalis (bases). Technically speaking, ph is the logarithm of the reciprocal (negative log) of the hydrogen ion concentration (hydrogen ion activity) in moles per liter.

  • Phase: A state of matter. This can be solid, liquid or gaseous.

  • Phosphorous: A plant nutrient that can cause an overabundance of bacteria and algae when high amounts are present, leading to a depletion of oxygen and fish kills. High levels of phosphorous in water are usually caused by agricultural runoff or improperly operating wastewater treatment plants. Also see nitrogen.

  • Photosynthesis: The manufacture by plants of carbohydrates and oxygen from carbon dioxide and water in the presence of chlorophyll, using sunlight as an energy source.

  • Phreatophytes: Plants that send their roots into or below the capillary zone to use ground water.

  • Physical and chemical treatment: Processes generally used in wastewater treatment facilities. Physical processes are for instance filtration. Chemical treatment can be coagulation, chlorination, or ozon treatment.

  • Physical weathering: Breaking down of parent rock into bits and pieces by exposure to temperature and changes and the physical action of moving ice and water, growing roots, and human activities such as farming and construction. Compare chemical weathering.

  • Phytoplankton: Usually microscopic aquatic plants, sometimes consisting of only one cell.

  • Piezometroc surface: The imaginary surface to which groundwater rises under hydrostatic pressure in wells or springs.

  • Pit Gauge or US Pit Gage:  a device to measure the depth of corrosion.  A pit gauge can take various forms, in the most basic as a simple lever and pointer or more accurate units using a dial or digital indicator to provide the measurement displacement.   Pit depth gauge, depth gauge, bridging bar.
  • Pilot tests: The testing of a cleanup technology under actual site conditions in a laboratory in order to identify potential problems before implementation.

  • Plankton: Tiny plants and animals that live in water.

  • Plate tectonics: Refers to the folding and faulting of rock and flow of molten lava involving lithospheric plates in the earth's crust and upper mantle.

  • Plenum flushes: Rinsing procedure that discharges deionized water from the rim of a flowing bath to remove contaminants from the sides and bottom of the bath.

  • Plug: Cement, grout, or other material used to fill and seal a hole drilled for a water well.

  • Plume: The area taken up by contaminant(s) in an aquifer.

  • Pluvial: Pertaining to precipitation.

  • POE-treatment: Point-Of-Entry treatment. Total water treatment at the inlet to an entire building or facility.

  • Point source: Source of pollution that involves discharge of wastes from an identifiable point, such as a smokestack or sewage treatment plant. Compare nonpoint source.

  • Polar substance: A substance that carries a positive or negative charge, for instance water.

  • Pollutant: A contaminant at a concentration high enough to endanger the life of organisms.

  • Pollution: Undesireable change in the physical, chemical, or biological characteristics of the air, water, or land that can harmfully affect the health, survival, or activities of human or other living organisms.

  • Polychlorinated biphenyls (PCBs): A group of chemicals found in industrial wastes.

  • Pond: A small natural body of standing fresh water filling a surface depression, usually smaller than a lake.

  • POP's: Persistent Organic Pollutants, complex compounds that are very persistent and difficultly biologically degradable.

  • Pore: An opening in a membrane or medium that allows water to pass through.

  • Porous: Something which allows water to pass through it. Compare nonporous.

  • Potable water: Potable water is considered safe for human consumption and is often referred to as drinking water. Freshwater that exceeds these chloride and dissolved solids limits is often referred to as slightly saline, brackish, or nonpotable water and is either diluted with fresher water or treated through a desalination process to meet potable-water standards for public supply.

  • Potentiation: The ability of one chemical to increase the effect of another chemical.

  • Potentiometric surface: The surface to which water in an aquifer can rise by hydrostatic pressure.

  • POU-treatment: Point-Of-Use treatment. Water treatment at a limited number of outlets in a building, for less than the whole building.

  • ppb - parts per billion: Number of parts of a chemical found in one billion parts of a solid, liquid, or gaseous mixture. Equivalent to micrograms per liter (ug/l).

  • ppm - parts per million: Number of parts of a chemical found in one million parts of a solid, liquid, or gaseous mixture. Equivalent to milligrams per liter (mg/l).

  • Precipitate: A solid which has come out of an aqueous solution. (ex., iron from groundwater precipitates to a rust colored solid when exposed to air).

  • Precipitation: Water falling, in a liquid or solid state, from the atmosphere to a land or water surface.

  • Precipitation process: The altering of dissolved compounds to insoluble or badly soluble compounds, in order to be able to remove the compounds by means of filtration.

  • Preservative: A chemical added to a water sample to keep it stable and prevent compounds in it from changing to other forms or to prevent microorganism densities from changing prior to analysis.

  • Pressure sewers: A system of pipes in which water, wastewater, or other liquid is pumped to a higher elevation.

  • Pre-treatment: Processes used to reduce or eliminate wastewater pollutants from before they are discharged.

  • Price at equilibrium: Where supply and demand curves intersect. The price at equilibrium is what allocates resources.

  • Price gouging: Excessive water rate increases that are unfair to water customers.

  • Pricing/rate structure: System used by water utility managers to charge customers for water usage.

  • Primary wastewater treatment: First step in wastewater treatment where screens and sedimentation tanks are used to remove most materials that float or settle. Primary treatment removes about 30 percent of carbonaceous biochemical oxygen demand from domestic sewage.

  • Priority date: The date of establishment of a water right. It is determined by adjudication of rights established before the passage of the water code. The rights established by application have the application date as the date of priority.

  • Process water: Water that serves in any level of the manufacturing process of certain products.

  • Product water: Water that has passed through a water treatment plant and is ready to be delivered to consumers.

  • Profundal zone: A lake's deep-water region that is not penetrated by sunlight.

  • Protons: Positively charged building blocks of an atom that are centered in the nucleus.

  • Protozoa: Large microorganisms, which consume bacteria.

  • Public supply: Water withdrawn by public and private water suppliers and delivered to users. Public suppliers provide water for a variety of uses, such as domestic, commercial, thermoelectric power, industrial, and public water use. See also commercial water use, domestic water use, thermoelectric power water use, industrial water use, and public water use.

  • Public water system: A system that provides piped water for human consumption to at least 15 service connections or regularly serves 25 individuals.

  • Public water use: Water supplied from a public-water supply and used for such purposes as firefighting, street washing, and municipal parks and swimming pools. See also public supply.

  • Public-supply deliveries: Water provided to users through a public-supply distribution system.

  • Public-water use: Water supplied from a public-water supply and used for such purposes as firefighting, street washing, and municipal parks and swimming pools. Public-water use also includes system water losses (water lost to leakage) and unusable water discharged from desalination or lime-softening facilities. Also referred to as utility-water use.

  • Puddle: A small pool of water, usually a few inches in depth and from several inches to several feet in its greatest dimension.

  • Pump: A device which moves, compresses, or alters the pressure of a fluid, such as water or air, being conveyed through a natural or artificial channel.

  • Pumped hydroelectric storage: Storing water for future use in generating electricity. Excess electrical energy produced during a period of low demand is used to pump water up to a reservoir. When demand is high, the water is released to operate a hydroelectric generator.

  • Purge: To force a gas through a water sample to liberate volatile chemicals or other gases from the water so their level can be measured.

  • Purgeable organics: Volatile organic chemicals which can be forced out of the water sample with relative ease through purging.

  • Putrefaction: Biological decomposition of organic matter; associated with anaerobic conditions.

  • Pyrogen: Substance that is produces by bacteria and it fairly stable. It causes fever in mammals.

Water glossary