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IMPELLERS: The semi-open or closed props or blades of a turbine pump that when rotated
generate the pumping force.
IMPERVIOUS: Not allowing, or allowing only with great difficulty, the movement of water.
In Series: Several components being connected one to the other without a bypass, requiring
each component to work dependent on the one before it.
INDICATOR: A special compound added to solution that changes color depending on the acidity
of the solution; different indicators have different colors and effective pH ranges.
INFECTIOUS PATHOGENS/MICROBES/GERMS: Are considered disease-producing bacteria,
viruses and other microorganisms.
Infiltration: The percolation of fluid into soil or formation. See also percolation.
INFORMATION COLLECTION RULE: ICR EPA collected data required by the Information
Collection Rule (May 14, 1996) to support future regulation of microbial contaminants,
disinfectants, and disinfection byproducts. The rule was intended to provide EPA with information
on chemical byproducts that form when disinfectants used for microbial control react with
chemicals already present in source water (disinfection byproducts (DBPs)); disease-causing
microorganisms (pathogens), including Cryptosporidium; and engineering data to control these
contaminants.
INITIAL MONITORING YEAR: An initial monitoring year is the calendar year designated by the
Department within a compliance period in which a public water system conducts initial monitoring
at a point of entry.
INORGANIC CHEMISTRY: A part of chemistry concerned with inorganic compounds.
INORGANIC COMPOUND: Compounds that do not contain carbon, though there are exceptions.
INORGANIC CONTAMINANTS: Mineral-based compounds such as metals, nitrates, and
asbestos. These contaminants are naturally-occurring in some water, but can also get into water
through farming, chemical manufacturing, and other human activities. EPA has set legal limits on
15 inorganic contaminants.
INORGANIC IONS: Present in all waters. Inorganic ions are essential for human health in small
quantities, but in larger quantities they can cause unpleasant taste and odor or even illness. Most
community water systems will commonly test for the concentrations of seven inorganic ions:
nitrate, nitrite, fluoride, phosphate, sulfate, chloride, and bromide. Nitrate and nitrite can cause an
illness in infants called methemoglobinemia. Fluoride is actually added to the drinking water in
some public water systems to promote dental health. Phosphate, sulfate, chloride, and bromide
have little direct effect on health, but high concentrations of inorganic ions can give water a salty
or briny taste.
INSOLUBLE COMPOUNDS: Are types of compounds cannot be dissolved. When iron or
manganese reacts with dissolved oxygen (DO) insoluble compound are formed.
INSULATOR: Material that resists the flow of electric current.
INTAKE FACILITIES: One of the more important considerations in the construction of intake
facilities is the ease of operation and maintenance over the expected lifetime of the facility. Every
intake structure must be constructed with consideration for operator safety and for cathodic
protection.
ION: A molecule that has gained or lost one or more electrons.
ION EXCHANGE: An effective treatment process used to remove iron and manganese in a water
supply. The hardness of the source water affects the amount of water an ion exchange softener
may treat before the bed requires regeneration.
IONIC BOND: Electrostatic attraction between oppositely charged ions.
IONIZATION: The breaking up of a compound into separate ions.
IRON AND MANGANESE: Fe and Mn In water they can usually be detected by observing the
color of the inside walls of filters and the filter media. If the raw water is pre-chlorinated, there will
be black stains on the walls below the water level and a black coating over the top portion of the
sand filter bed. When significant levels of dissolved oxygen are present, iron and manganese
exist in an oxidized state and normally precipitate into the reservoir bottom sediments. The
presence of iron and manganese in water promote the growth of Iron bacteria. Only when a water
sample has been acidified then you can perform the analysis beyond the 48 hour holding time.
Iron and Manganese in water may be detected by observing the color of the of the filter media.