Small Systems Water Treatment Plant Operator Program Manual

SMALL
SYSTEMS
WATER
SOURCES
& CHARACTERISTICSC
& C
Surface water is found in lakes and rivers. Its quality and availability varies with the
season. Surface water can be influenced by many sources and become quickly
contaminated. Such sources include: natural runoff from the land, spills of fuel or
chemicals, large upstream sewage discharges, discharges from mining, or agriculture.
3
Groundwater is found in the underground, usually in an aquifer. Because it has
filtered through the earth, groundwater is usually very clear and free from
microorganisms. However, because water is a solvent, it dissolves minerals such as
calcium, iron and manganese, which can affect the taste and quality of the water.
Groundwater that is associated with organic soils may contain hydrogen sulphide
and/or methane.
Groundwater from shallow wells can be influenced by surface conditions. If the
surface water that feeds the shallow well is contaminated, the ground water may be
contaminated as well. Sometimes this contamination can be sudden, coming and going
quickly. Or, it can be slow and once contaminated, take many years before it becomes
clean again.
3.4 GENERAL PROPERTIES OF WATER
Water is never found in its pure form in nature. This is because water provides a place
for plants and animals to live, and because it is a solvent. As a result, water dissolves
tiny amounts of elements and other natural compounds. These include organic matter,
various microorganisms and plants, and other substances. These factors contribute to
how we see, taste and smell water.
All of these factors contribute to whether the water is potable. Water that is potable is
safe for human consumption according to recognized standards.
3.5 MICROBIOLOGICAL CHARACTERISTICS
Surface water, that is water found in lakes and rivers, contain many different types of
microscopic organisms. Many of these organisms are a natural part of the
environment. Others, and the ones in which we are interested, come from man and
animals. Some of these organisms are called pathogenic, meaning they are harmful
and cause disease. Because the disease is associated with water, it is called a waterborne
disease. Some of the diseases include: typhoid; cholera; and giardiasis.
This is why it is necessary that all public water supplies are disinfected. People should
only drink water that has been disinfected, or boiled.
Water microbiology by definition is the study of microbes found in natural water.
There are many types of micro organisms that are found naturally in water, including
bacteria, viruses, protozoa, algae, and microscopic animals. The vast majority of these
11/03
03/03
3-3