Civil Engineering Reference
In-Depth Information
compromised immune systems (the very young, very old, cancer patients, AIDS pa-
tients, etc.) are likely to have more severe symptoms.
Cryptosporidium
A protozoan organism (2-6 microns in size) found in most wa-
tersheds and surface waters where human or animal activity occurs. The organism is
surrounded by an protective outer shell called an oocyst, can lie dormant in the en-
vironment for many years, and is highly resistant to disinfection.
Disinfection By-products (DBPs)
The class of chemicals that are formed when dis-
infectants react with the organic compounds in water. Some of these compounds are
carcinogens, and some are suspected of causing acute health effects.
Gastroenteritis
A broad term used to describe illness associated with the stomach
and intestines that may be caused by drinking water contaminated with pathogenic
(disease-causing) microorganisms, such as viruses, bacteria, or protozoa. Symptoms
may include nausea, vomiting, cramps, diarrhea, and fatigue.
Giardia lamblia
A protozoan organism (5-12 microns in size), frequently found in
watersheds and surface waters, that may cause gastroenteritis if consumed.
Inorganic Chemicals (IOCs)
Broad category of naturally occurring mineral-based
elements, such as metals, radionuclides, and nitrates that can be found in drinking
water.
Maximum Contaminant Level (MCL)
The highest level of a specific compound
that is allowed in treated drinking water. MCLs are established by regulation and are
set as close to the MCLG as possible using the best available technology (BAT) to
remove the contaminant. MCLs are enforceable standards and, if violated by a public
water supplier, may result in fines and or inprisonment.
Maximum Contaminant Level Goal (MCLG)
The level of a specific compound in
drinking water below which no adverse health effects are expect to occur. MCLGs are
derived using either observed or predicted health endpoints and are nonenforceable
public health goals.
Microbes (Microorganisms)
Tiny living organisms that cannot be seen with the
naked eye, and are capable of causing disease or illness.
National Primary Drinking Water Regulations (NPDWRs)
Legally enforceable
standards established by US EPA that apply to all public water systems. These stan-
dards protect the consumers of drinking water by limiting the levels of harmful con-
taminants allowed in the treated water.
National Secondary Drinking Water Regulations (NSDWRs)
Non-enforceable
federal guidelines regarding the aesthetic effects (i.e., non-health-based) of drinking
water, such as taste, color, odor, etc.
Non-community Water Systems
A public water system that serves customers on
less than a year-round basis. There are two types of noncommunity systems, and they
are generally very small systems (serving less than 500 people): Approximately 96,000
transient systems
serve water to people on an infrequent, temporary basis, such as
those at gas stations, restaurants, etc. Approximately 20,000
nontransient systems
serve the same people for more than 6 months in a year, such as those at schools and
factories.
Organic Chemicals
Carbon-based, manmade chemicals, such as solvents and pes-
ticides, which can get into a water supply through runoff from cropland or discharge
from factories.
