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Water Glossary - U

  • Ultra-violet (UV) oxidation: A process using extremely short wave-length light that can kill micro-organisms (disinfection) or cleave organic molecules (photo oxidation) rendering them polarized or ionized and thus more easily removed from the water.

  • Unclassified waters: Those waters for which no classification has been assigned and which have not been identified in Appendix A of 31 Texas Administrative Code, Chapter 307.10 of Title 31 (relating to definitions).

  • Unconsolidated formations: Naturally occurring earth formations that have not been lithified. Alluvium, soil, gravel, clay, and overburden are some of the terms used to describe this type of formation.

  • Undercurrent: A current below the upper currents or surface of a fluid body.

  • Underdrain: A concealed drain with openings through which the water enters when the water table reaches the level of the drain.

  • Underflow: Movement of water through subsurface material.

  • Underground storage tank: A tank located all or partially underground that is designed to hold gasoline or other petroleum products or chemical solutions.

  • Undertow: The current beneath the surface that sets seaward or along the beach when waves are breaking on the shore.

  • Underwater: Under the surface of the water; lying, growing, performed, worn, or operating below the surface of the water, as underwater caverns, underwater operation of a submarine.

  • Unit surcharge: A surcharge imposed for all water use above a threshold level for excess consumption established based on average per capita or per-household consumption.

  • Unloading: The release of the contaminant that was captured by a filter medium.

  • Unsaturated Zone: The area above the water table where soil pores are not fully saturated with water.

  • Upflow: An upward flow.

  • Upwater: Ultra pure water creation demands a specialised way of working. A number of techniques are used amongst others; membrane filtration, ion exchanges, sub micron filters, UV and ozone systems. The produced water is extremely pure and contains none to very low concentrations of salts, organic/ pyrogene components, oxygen, suspended solids and bacteria.

  • Urban runoff: Storm water from city streets and adjacent domestic or commercial properties that may carry pollutants of various kinds into the sewer systems and/or receiving waters.

  • USGS: United States Geological Survey.

  • Utility: Public water service provider.

  • UV: Ultra Violet. Radiation that has a wavelength shorter than visible light. It is often used to kill bacteria and destroy ozone.

Water glossary