Download Water To Drink

Lesson 2
Water Quality
 Certain substances, such as ion, can affect the taste or
color of water but are harmless unless present at very
high levels. Other substances, such as certain
chemicals and microorganisms can be harmful to your
health.
 In the U.S. the _________________________________
is responsible for developing water-quality standards.
Acidity
 The pH level of water also affects its quality.
 The pH of water is a measurements of how
__________________ or ___________ the water is on a
scale of 0-14.
 ______________ has a pH of 7, it is neutral, meaning it
neither an acid or nor a base.
 The _______________ the pH, the more basic the
water.
 The _______________ the pH, the more acidic the
water.
Hardness
 The combines level of two minerals ________________
and _________________, in a sample of water is
referred to as the hardness of that sample of water.
 Hard water does not form suds easily.
Disease-Causing Organisms
 The presence of disease-causing organisms affects
water quality.
 Such organisms can be detected in water by
conducting a __________________, which measure the
number of Escherichia coli bacteria.
 A high coliform count is a sign that the water may also
contain other disease-causing organisms.
Treating Drinking Water
 Water from both public and private supplies often
needs some treatment to ensure that it is clean and
safe to drink.
Filtration and Coagulation
 The first step in treating water from a lake or river is
usually _________________.
 In the second step, a chemical is added to cause sticky
globs, called ______________, to form. Other particles
stick to this substance. This process is known as
_____________________.
Chlorination and Aeration
 The next step is to chlorinate your water.
 Chlorine is added to drinking water for the same
reason it is added to swimming pools: to kills diseasecausing microorganisms.
 After chlorination, ______________ is then forced
through the purified water. The process reduces
unpleasant odors and tastes from your water.
Testing Samples
 __________________________ regularly test samples
of water from treatment plants to assess water quality.
 They test for the substances covered by the drinkingwater standards, including chemicals, dissolved solids,
pH, hardness, and disease-causing microorganisms.
Treating Wastewater
 Two ways communities deal with sewage are
wastewater treatment plants and septic systems.
 _____________________ sewers carry sewage away to
wastewater treatment plants.
 Sewage flows into a _________________, where
bacteria breakdown the waste material into simpler
chemicals. Cleaner water leaves the tank and flows
into a ____________________.
Questions for Thought
 What is a leach field?
 What is the goal of drinking-water treatment?
 What two minerals affect a water sample’s hardness?